Preheat oven to 400 degrees. Heat your pan (my absolute fave!) on medium heat on stovetop. Add 2 T of the butter to the pan. After butter melts, add onion, sausage and broccoli, and cook for 5-7 minutes. Then add 1 T more of butter and mushrooms to pan. Cook mushrooms for ~ 3 mins.
While pan ingredients are cooking, whisk together eggs, milk, cheese, and salt/pepper in a bowl. Pour egg mixture into pan and spread evenly over the ingredients. Cook on stovetop for 3 minutes (no stirring!) until edges start to set.
Carefully place pan in oven and cook for 10 minutes. The sausage frittata is done when eggs appear set and frittata is separating a bit from the edges of the pan. Let cool a bit, slice, and serve!
Notes
🥚 Cook the egg mixture on low to medium heat to prevent eggs from browning.🥚 Make sure your skillet is oven-safe before placing your frittata in the oven.🥚 To plate...cut sausage frittata into 6 pie-like slices. You can have your frittata with some toast and/or a yogurt sundae (yogurt, mixed fruit, and drizzle of honey) on the side.🥚 If you don't have some of these ingredients, use what you got. Within reason, you can put almost anything in a frittata. Just note that denser ingredients require a bit more cook time.