Preheat your oven to 375°F. Spray a 9x13 inch baking dish generously with nonstick cooking spray, coating the corners and sides.

If chicken breasts are uneven in thickness, place each between two sheets of plastic wrap or parchment paper. Use a meat mallet or heavy skillet to gently pound the thicker end until the entire piece is 3/4 to 1 inch thick throughout.

Sprinkle both sides of each chicken breast with 1/2 cup of the grated Parmesan cheese, black pepper, and a light pinch of salt. Arrange the seasoned breasts in the prepared baking dish with space between each piece if possible.

In a small bowl, whisk together the Caesar dressing and sour cream until completely smooth. Pour this sauce over each chicken breast, using a spoon to spread it evenly across the top and sides. Sprinkle the remaining 1/2 cup of Parmesan cheese over the sauce layer.

Bake uncovered for 20 minutes. The chicken should be mostly cooked through and the sauce will bubble gently around the edges.

While the chicken bakes, melt the butter in a small bowl. Add the panko breadcrumbs or crushed croutons and stir until all crumbs are coated. For extra flavor, mix in additional Parmesan, black pepper, or garlic powder if desired.

After 20 minutes, remove the baking dish from the oven. Sprinkle the buttered breadcrumb mixture evenly over the top of each chicken breast, creating a uniform layer.

Return the dish to the oven and bake for an additional 10 minutes.

Switch the oven to broil. Position the baking dish about 6 inches from the broiler element. Broil for 1-2 minutes, watching constantly, until the breadcrumb topping turns golden brown.

Remove from oven and loosely tent with aluminum foil. Let the chicken rest for 5-10 minutes before serving to allow juices to redistribute.