Preheat and prep pans. Heat your oven to 425°F (220°C). Lightly grease a baking dish or sheet pan.
Pat the chicken dry with paper towels so it browns better.
Season the chicken. Drizzle with olive oil, then sprinkle garlic powder, onion powder, Italian seasoning, salt, and pepper on both sides. Rub it in for even coverage.
Quick sear (optional, but great). For extra flavor and moisture, sear chicken in a hot skillet for 2–3 minutes per side before baking. If you prefer to skip this step, go straight to the oven.
Bake the chicken. Arrange chicken in a single layer.
Bake 12–15 minutes, depending on thickness. You want it almost cooked through but not fully done yet.
Add the “pizza” layer. Spoon marinara over each piece, about 2–3 tablespoons per chicken breast. Top with mozzarella, a sprinkle of Parmesan, and 6–8 pepperoni slices per piece.
Finish baking. Return to the oven for 6–10 minutes, until the cheese is melted and bubbly and the chicken hits an internal temp of 165°F (74°C).
Broil for color (optional). Broil 1–2 minutes for golden, blistered cheese.
Watch closely to avoid burning.
Rest and garnish. Let the chicken rest for 5 minutes. Add fresh basil or parsley and a pinch of red pepper flakes if you like heat.
Portion for meal prep. Slice or leave whole. Divide among 4 airtight containers.
Add your chosen sides (see variations for ideas).