Preheat the oven to 400℉.
Whisk the eggs and scramble in a small skillet over medium heat. Set aside.
Cook the breakfast sausages, slice into 1/4 inch rounds, and set aside.
In a small saucepan, melt the butter over medium heat.
Whisk in the flour and cook for 3-4 minutes to create a roux.
Add the salt, pepper, and nutmeg to the roux.
Slowly add the milk, whisking continuously. Heat until thickened.
Pour the sauce onto the pizza crust and spread, leaving a half inch around the outside.
Top the pizza with scrambled eggs, sliced sausage, diced onions, diced bell pepper, and sliced mushrooms.
Add the cheese on top of all the other ingredients.
Bake in the preheated oven for about 5 minutes, just long enough to melt the cheese.
Remove from the oven, slice, and serve immediately.