In a large bowl, whisk the egg until beaten. Add the breadcrumbs, cheeses, basil, garlic, Italian seasoning, salt, and pepper flakes. Mix to combine.
1 large egg, ¾ cup breadcrumbs, ¼ cup grated Parmesan cheese, ¼ cup shredded mozzarella cheese, 2 tablespoons chopped fresh basil, 2 cloves garlic, 2 teaspoons dried Italian seasoning, 1 teaspoon kosher salt, ½ teaspoon crushed red pepper flakes