Step 1

Preheat oven to 350 degrees. Spray an 8" X 8" baking pan with nonstick spray.

Step 2

Pound chicken to 1/2-inch thickness. Season with salt and black pepper. Bring an extra-large skillet sprayed with nonstick spray to medium heat. Cook for about 4 minutes per side, until cooked through. Transfer to a cutting board.

Step 3

Meanwhile, in a large bowl, combine cream cheese with 1/4 tsp. garlic powder and 1/4 tsp. onion powder. Stir until smooth and uniform.

Step 4

Remove skillet from heat; clean, if needed. Re-spray, and bring to medium-high heat. Add mushrooms and bell pepper, and sprinkle with remaining 1/4 tsp. garlic powder and 1/4 tsp. onion powder. Cook and stir until slightly softened and lightly browned, about 6 minutes.

Step 5

Transfer skillet contents to the bowl with the cream cheese mixture. Mix thoroughly.

Step 6

Chop chicken, and evenly place in the baking pan.

Step 7

Evenly top chicken with creamy veggies, marinara sauce, mozzarella, and chopped pepperoni.

Step 8

Bake until entire dish is hot and bubbly and mozzarella has melted, 20 - 25 minutes.