Cook the Pasta: Bring a large pot of salted water to a boil. Add your linguine and cook according to package directions until al dente (tender but still with a slight bite). Drain and set aside, reserving about 1/2 cup of the pasta water.
Prep the Chicken: While the water heats, slice or cube your chicken breasts. Pat them dry with paper towels – this helps them brown nicely. Season generously with salt, pepper, garlic powder, onion powder, cayenne pepper, smoked paprika, and red pepper flakes.
Cook the Chicken: Heat the olive oil and 1 tbsp butter in a large skillet or pot over medium-high heat. Add the seasoned chicken in a single layer. Cook for 3-5 minutes per side, depending on thickness, until golden brown and cooked through. Remove the chicken from the skillet and set aside.
Make the Sauce: Reduce the heat to medium. Add the remaining 1/2 cup unsalted butter to the same skillet. Once melted, add the remaining garlic powder, onion powder, cayenne, smoked paprika, red pepper flakes, salt, and pepper. Stir for about 30 seconds until fragrant.
Build the Sauce: Pour in the chicken broth, Dijon mustard, and lemon juice. Stir well, scraping up any browned bits from the bottom of the pan (that's flavor!). Let it simmer gently for 1-2 minutes to thicken slightly.
Add Cream and Cheese: Reduce heat to low. Stir in the heavy cream and grated Parmesan cheese. Stir constantly until the cheese is melted and the sauce is smooth and creamy. Don't let it boil rapidly once the cream is added.
Combine Everything: Add the cooked linguine and the cooked chicken back into the skillet with the sauce. Toss gently to coat everything evenly. If the sauce seems a little too thick, add a tablespoon or two of the reserved pasta water until it reaches your desired consistency.
Serve: Garnish with fresh chopped parsley. Serve immediately and watch it disappear!