1. Preheat oven to 350 degrees Fahrenheit and drizzle a large baking pan with oil.
2. Combine egg, mayo, and flour in a medium-sized bowl. In another bowl, combine cornflake crumbs, garlic powder, onion powder, paprika, and parsley. Dip the chicken in the egg mixture and then coat with cornflake crumb mixture.
3. Place coated chicken in prepared pan and flip over so that both sides are coated with oil. If pan is too small, use a second pan—do not overlap pieces.
4. In a frying pan, sauté sliced onions in oil for six minutes over medium heat. Add garlic, tomatoes, basil, and salt and pepper to taste. Cover pan and cook on medium heat for 10 minutes. Pour tomato mixture over chicken, cover pan and bake for 30 minutes.