Preheat the oven: Set to 400°F (200°C).
Lightly oil or spray a 9x13-inch baking dish.
Prep the chicken: Pat the chicken dry with paper towels. If using thick breasts, slice them horizontally to create thinner cutlets or pound to even thickness (about 3/4 inch). Season both sides with a pinch of salt and pepper.
Make the topping: In a bowl, mix the mayonnaise, parmesan, garlic, lemon juice, Dijon (if using), paprika, Italian seasoning, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.
Stir until smooth.
Assemble: Arrange the chicken in the baking dish. Spread the mayo-parmesan mixture evenly over the top of each piece, covering edge to edge. Don’t leave bare spots—this helps lock in moisture.
Bake: Place on the middle rack and bake for 18–25 minutes, depending on thickness.
Start checking at 18 minutes. The chicken is done when an instant-read thermometer shows 165°F (74°C) in the thickest part.
Optional broil: For extra color, switch to broil on high for 1–2 minutes at the end. Keep a close eye to avoid burning.
Rest and garnish: Let the chicken rest for 5 minutes.
Sprinkle with chopped parsley or chives for freshness.
Serve: Plate with a wedge of lemon. Great with roasted broccoli, Caesar salad, garlic green beans, or buttered orzo.