Preheat oven to 350 degrees F. Cut each chicken breast to half the thickness. In a shallow bowl or dish, mix the egg and buttermilk together. In another shallow bowl or dish, mix bread crumbs, cheddar cheese, and Parmesan cheese. Dip each breast into egg mixture and then into the bread crumb mixture. Place chicken breasts into a baking dish. Mix the melted butter and minced garlic into a small bowl and drizzle over the chicken. Sprinkle salt and pepper on top. Bake for 30 minutes.