Evenly pound chicken to 1/4-inch thickness. Season with salt and pepper.
Bring a skillet sprayed with nonstick spray to medium heat. Cook chicken for 3 - 4 minutes per side, until cooked through.
Meanwhile, to make the sauce, combine these ingredients in a small bowl: crushed tomatoes, garlic powder, and onion powder. If you like, add salt and pepper. Mix well.
While still in the skillet, top chicken with sauce, and sprinkle with cheese. Top with pepperoni.
Cover and cook for 2 minutes, or until sauce is hot and cheese has melted.