Introduction

Oh my goodness, have you ever just craved those iconic flavors? You know the ones – that special sauce, the beefy goodness, the pickles, the onions… it’s pure comfort food nostalgia. But if you’re living the low-carb life, that drive-thru dream feels pretty far away, right?

Well, get ready to have your mind blown and your taste buds singing! I’ve whipped up a recipe that takes all those amazing Big Mac vibes and transforms them into a super easy, incredibly satisfying, low-carb casserole. Seriously, this Keto Big Mac Casserole Bake is a total game-changer. It’s quick enough for a weeknight, packed with flavor, and honestly, it feels a little bit like magic how well it captures that classic taste.

Why You’ll Love This Recipe

Fast: From start to oven in about 20 minutes? Yes, please! Perfect for those busy nights.
Easy: If you can brown meat and chop a few veggies, you can make this. It’s truly beginner-friendly.
Giftable/Shareable: While maybe not traditionally giftable raw, a baked casserole is always a welcome sight at a potluck or when bringing dinner to a friend. It feeds a crowd easily!
Crowd-Pleasing: Even folks not doing keto will devour this! It has all the familiar, delicious flavors everyone loves.
Low Carb & Keto-Friendly: Enjoy all the flavor without derailing your goals. Win-win!

Ingredients

Here’s what you’ll need to gather to make this weeknight hero happen. Most of these are probably already in your low-carb pantry and fridge!

1 lb Zucchini: Our fabulous low-carb base layer. When sliced thin, it softens up perfectly and absorbs all the yummy flavors.
2 tbsp Olive oil (for zucchini): Just a little drizzle to help the zucchini cook down and get flavorful.
1/4 tsp Sea salt (for zucchini): Helps draw out moisture and season the zucchini.
1 1/2 lbs Ground beef: The star of our meaty layer! Go for 80/20 or 85/15 for best flavor.
1/2 tbsp Olive oil (for meat): To help brown that beautiful beef.
1/2 tbsp Sea salt (for meat): Essential seasoning!
1/2 tsp Black pepper: Adds just the right amount of warmth and spice.
1/2 large Onion, diced: Sautéed onion adds amazing depth of flavor to the meat layer.
3/4 cup Sugar-free thousand island dressing (for assembly): This is our “special sauce” layer! Make sure it’s sugar-free to keep it keto-friendly.
2 cups Cheddar cheese, shredded: Because what’s a casserole without glorious melted cheese? Sharp or mild, your choice!
1 1/2 cups Iceberg lettuce, shredded: The classic Big Mac crunch! Added fresh after baking.
1 medium Roma tomato, diced: Adds freshness and a touch of acidity on top.
3/4 cup Pickles, sliced: Dill pickles are a must for that signature tangy bite!
1/4 cup Sugar-free thousand island dressing (for topping): A final drizzle of that special sauce right before serving.
1/2 tbsp Sesame seeds: That little touch that screams “Big Mac”! Don’t skip it.

How to Make It

Okay, let’s get this deliciousness assembled! It comes together in a few simple layers.

First things first, get your oven preheating to a cozy 375°F (190°C).
Grab your sliced zucchini rounds. Pop them in a bowl and toss them with that 2 tbsp of olive oil and 1/4 tsp of sea salt. Make sure they’re nicely coated.
Now, heat up that 1/2 tbsp of olive oil in a large skillet over medium-high heat. Add your ground beef and start browning it, breaking it up with your spoon as you go. Once it’s all browned up, drain off any excess fat. We want flavor, not grease!
Toss the diced onion into the skillet with the cooked beef. Let them cook together for about 5-7 minutes, or until the onion is nice and softened. Season this delicious meat mixture with the remaining 1/2 tbsp sea salt and 1/2 tsp black pepper. Give it a good stir.
Time to layer! Arrange those seasoned zucchini rounds in the bottom of your chosen baking dish. They don’t have to be perfect, just a relatively even layer.
Spread the cooked ground beef and onion mixture evenly over the top of the zucchini layer.
Now for the “special sauce” layer! Drizzle or spread 3/4 cup of your sugar-free thousand island dressing right over the meat layer.
Sprinkle that glorious shredded cheddar cheese evenly over the dressing layer. We’re building flavor here!
Pop the casserole into your preheated oven. Bake for 20-25 minutes. You’ll know it’s ready when the cheese is beautifully melted, golden, and bubbly around the edges, and everything is heated through.
Carefully remove the hot casserole from the oven and let it stand for a few minutes. This helps it set slightly and makes it easier to serve.
Here’s the key for that fresh Big Mac experience! Just before you’re ready to serve, sprinkle the shredded lettuce, diced tomato, and sliced pickles all over the top. Give it a final drizzle with the remaining 1/4 cup of sugar-free thousand island dressing, and sprinkle those sesame seeds over everything.

Scoop out a generous portion and enjoy that incredible low-carb Big Mac flavor!

Substitutions & Additions

This recipe is super flexible! Here are a few ideas to make it your own:

Veggies: Don’t have zucchini or want to change it up? Try using riced cauliflower (drain very well!), broccoli florets, or even a layer of sautéed mushrooms as your base. You could also skip the veggie base entirely for a simpler meat-and-cheese bake, but the zucchini is a nice addition!
Cheese: Monterey Jack, Colby Jack, or a blend would work beautifully instead of or mixed with the cheddar.
Meat: Ground turkey or chicken could be used, but ground beef really gives you that classic Big Mac taste.
Dressing: If you can’t find a sugar-free thousand island, you can easily make your own keto-friendly version using sugar-free ketchup, mayo, relish, and a dash of apple cider vinegar.
Spice: Add a pinch of cayenne pepper or red pepper flakes to the meat layer if you like a little heat.
Extra Flavor: A sprinkle of onion powder and garlic powder in the meat mix never hurt anyone! You could also crumble cooked bacon over the top with the fresh toppings. Bacon cheeseburger Big Mac, anyone?!

Tips for Success

Making this casserole is a breeze, but a few little tips can ensure it turns out perfectly every time:

Don’t Skip Draining the Beef: Excess fat can make the casserole greasy. Drain it well after browning.
Season the Zucchini: Tossing the zucchini in oil and salt helps it soften nicely and ensures it’s not bland.
Layer Order Matters: Putting the dressing under the cheese helps it stay moist and meld into the meat layer as it bakes.
Wait on Fresh Toppings: This is CRUCIAL! Adding the lettuce, tomato, and pickles after baking keeps them fresh, crisp, and vibrant, giving you that essential Big Mac texture contrast.
Let it Rest: Giving the casserole a few minutes out of the oven helps the layers set so it doesn’t fall apart when you scoop it.

How to Store It

Got leftovers? Lucky you! This casserole stores really well.

Store any remaining casserole without the fresh toppings in an airtight container in the refrigerator for up to 3-4 days. When reheating, you can warm individual portions in the microwave or cover the dish and reheat in the oven until heated through. Add fresh lettuce, tomato, pickles, and dressing to the reheated portions.

I don’t recommend freezing this casserole once the zucchini base is cooked, as the zucchini can become watery and mushy upon thawing. It’s best enjoyed fresh within a few days!

FAQs

Is this casserole really keto-friendly?

Yes! By using zucchini as the base and sugar-free thousand island dressing, we keep the carb count low while delivering all the beloved Big Mac flavors. Always check the nutrition labels of your specific ingredients, especially the dressing, to be sure.

Can I make this ahead of time?

You can definitely prep the casserole layers (zucchini, meat, dressing, cheese) ahead of time and keep it covered in the fridge for up to 24 hours before baking. Don’t bake it until you’re ready to eat, and add the fresh toppings only after baking and just before serving.

Why add the toppings after baking?

Adding the lettuce, tomato, and pickles after baking is key to replicating the Big Mac experience! It keeps the lettuce crisp, the tomato fresh, and the pickles tangy. If you baked them, they would become wilted, mushy, and lose their vibrant flavor and texture.

Can I use ground turkey instead of beef?

You can, but for the most authentic “Big Mac” flavor, ground beef is definitely the way to go. If you use turkey, you might want to add a little extra seasoning (like onion powder and garlic powder) to boost the flavor profile.

Easy Keto Big Mac Casserole Bake

This recipe transforms the iconic Big Mac flavors into a super easy, satisfying, low-carb casserole. It's quick enough for a weeknight, packed with flavor, and delivers that classic taste without derailing low-carb goals.

Print Recipe Pin Recipe

Prep Time 20

Cook Time 20

Equipment

Large skillet
Baking dish
bowl

Ingredients

1 lb Zucchini sliced thin
2 tbsp Olive oil for zucchini
0.25 tsp Sea salt for zucchini
1.5 lbs Ground beef 80/20 or 85/15
0.5 tbsp Olive oil for meat
0.5 tbsp Sea salt for meat
0.5 tsp Black pepper
0.5 Large Onion diced
0.75 cup Sugar-free thousand island dressing for assembly
2 cups Cheddar cheese shredded
1.5 cups Iceberg lettuce shredded
1 Medium Roma tomato diced
0.75 cup Pickles sliced dill pickles
0.25 cup Sugar-free thousand island dressing for topping
0.5 tbsp Sesame seeds

Instructions

First things first, get your oven preheating to a cozy 375°F (190°C).
Grab your sliced zucchini rounds. Pop them in a bowl and toss them with that 2 tbsp of olive oil and 1/4 tsp of sea salt. Make sure they're nicely coated.
Now, heat up that 1/2 tbsp of olive oil in a large skillet over medium-high heat. Add your ground beef and start browning it, breaking it up with your spoon as you go. Once it's all browned up, drain off any excess fat.
Toss the diced onion into the skillet with the cooked beef. Let them cook together for about 5-7 minutes, or until the onion is nice and softened. Season this delicious meat mixture with the remaining 1/2 tbsp sea salt and 1/2 tsp black pepper. Give it a good stir.
Time to layer! Arrange those seasoned zucchini rounds in the bottom of your chosen baking dish. They don't have to be perfect, just a relatively even layer.
Spread the cooked ground beef and onion mixture evenly over the top of the zucchini layer.
Now for the "special sauce" layer! Drizzle or spread 3/4 cup of your sugar-free thousand island dressing right over the meat layer.
Sprinkle that glorious shredded cheddar cheese evenly over the dressing layer.
Pop the casserole into your preheated oven. Bake for 20-25 minutes. You'll know it's ready when the cheese is beautifully melted, golden, and bubbly around the edges, and everything is heated through.
Carefully remove the hot casserole from the oven and let it stand for a few minutes. This helps it set slightly and makes it easier to serve.
Just before you're ready to serve, sprinkle the shredded lettuce, diced tomato, and sliced pickles all over the top. Give it a final drizzle with the remaining 1/4 cup of sugar-free thousand island dressing, and sprinkle those sesame seeds over everything.
Scoop out a generous portion and enjoy that incredible low-carb Big Mac flavor!

Notes

Store any remaining casserole without the fresh toppings in an airtight container in the refrigerator for up to 3-4 days. Reheat individual portions in the microwave or cover and reheat in the oven. Add fresh lettuce, tomato, pickles, and dressing to reheated portions. Do not freeze this casserole with the zucchini base, as it can become watery upon thawing. Always check nutrition labels of specific ingredients for keto-friendliness, especially dressing. You can prep casserole layers (zucchini, meat, dressing, cheese) up to 24 hours ahead and store in the fridge before baking.