Ideal for prepping ahead of time, this protein-packed breakfast frittata is easy to customize and loaded in flavor. This version is made with sausage, peppers and cheese but feel free to use any meat or veggies you have on hand. It's delicious served warm, room temperature or chilled.
Pre-heat oven to 400 degrees and heat a medium skillet over medium-high heat. Add butter to pan to melt then add onions, peppers and pinch of salt and pepper. Saute until caramelized, stirring frequently, about 7-9 minutes. Remove from pan, set aside.
To the same pan, add breakfast sausage and cook until browned through, about 6-7 minutes, using a wooden spoon to break up in to bite-sized pieces.
While sausage is browning, in a medium bowl, whisk together eggs, salt, pepper and milk. Return caramelized peppers and onions back to the pan along with the cooked sausage and stir well.
Pour egg mixture on top of the sausage and veggies in the skillet and stir two or three times to incorporate. Sprinkle cheddar cheese on top then bake in the oven until eggs are cooked through and fully set, about 12-14 minutes.
Garnish with minced scallions and serve immediately or let cool and keep in the refrigerator in an air-tight container for up to 5 days.