Preheat oven to 375 degrees F. Line baking sheet with silicone mat or parchment paper.
In one shallow bowl, use a fork to beat egg with onion powder, salt, garlic powder, and pepper.
In another shallow bowl, stir together flour, parmesan cheese, basil, and oregano.
Dip each chicken piece into egg mixture, and allow excess egg to drip off. Then, press egg-coated chicken into the flour/parmesan mixture, coating all sides evenly.
Place coated chicken pieces in a single layer on the prepared baking dish. (Sprinkle a little extra flour mixture over any spots you missed.) Bake in preheated oven for 20-25 minutes or until golden brown. (Chicken should be cooked to an internal temperature of 165 degrees F.)
Carefully remove pan from oven. Spread marinara sauce evenly over the top of each piece of chicken, and arrange the cheese slices over the sauce. (I tear the cheese slices to fit the chicken.)
Return chicken to the oven and bake about 5 minutes longer, or until cheese is melted. Serve warm.