Preheat oven to 375 degrees F (190 degrees C). Grease 12 muffin cups with cooking spray.
Heat a large skillet over medium-high heat. Cook and stir bratwurst in the hot skillet until browned and crumbly, 5 to 7 minutes; drain on a paper towel-lined plate. Season bratwurst with 2 teaspoons Italian seasoning and black pepper.
Whisk eggs and milk together in a bowl; add 1 1/2 teaspoons Italian seasoning, garlic powder, seasoned salt, and garlic salt. Stir bratwurst and Mexican cheese blend into egg mixture. Pour egg mixture into the prepared muffin cups.
Bake in the preheated oven until muffin cakes are set in the middle, 35 to 40 minutes.