First things first, get your oven ready. Preheat it to 400°F (that's 200°C). Then, grab your 12-cup muffin tin. You can either line it with cute paper liners (makes for easy cleanup!) or grease each cup really well. This prevents sticking and ensures your beautiful muffins pop right out.

In a big bowl, let's mix the dry ingredients. Whisk together the cornmeal, all-purpose flour, baking powder, salt, and if you're using it, the garlic powder. Just give it a good whisk to make sure everything is combined and there are no big lumps of baking powder.

Now, in a separate, medium-sized bowl, whisk together the wet ingredients: the eggs, milk (or buttermilk), and vegetable oil. Give them a good mix until they're well combined.

Here's the crucial part for tender muffins: Pour the wet ingredients into the bowl with the dry ingredients. Now, using a spatula or a spoon, stir them together until they are just moistened. Seriously, stop as soon as you don't see dry flour pockets. A few lumps are perfectly fine – in fact, they're a sign you haven't overmixed, which means your muffins will be light and fluffy, not tough.

Time for the good stuff! Gently fold in the shredded cheddar cheese and the chopped jalapeños. "Folding" just means using your spatula to scoop from the bottom and bring it up, turning the mixture over gently. This distributes the cheese and peppers without developing the gluten too much.

Divide that glorious batter evenly among the prepared muffin cups. Fill each cup about two-thirds full. This gives them room to rise nicely without spilling over.

Pop the tin into your preheated oven. Bake for 18 to 22 minutes. You'll know they're ready when the tops look golden brown and beautiful. To be sure, insert a wooden skewer or toothpick into the center of one of the muffins – it should come out clean.