Cheesy Egg Thingy

My dad makes the original cheesy egg thingy in a pan started on the stove and finished in the broiler. It usually contains only egg and cheese (sometimes meat) and a side of toppings, but I’m too lazy to do all the sides separate. This version was super simple and Derek loved it. Here’s what’s in it:
Carmelized Onions
Sausage links cut up
Apple cut up
7 eggs whisked with a squirt of milk and mustard.
Cheddar cheese on top (added halfway through the baking)
Baked at 400 til the middle is set.

(PS I did make a cake. It was yummy and I made Derek take the rest to work to give away. Thanks Kaykers for the cake flour tip. Mmmmm)