1.8 cups cheese shredded divided (such as Cheddar or Swiss)
Equipment
frying pan
sauce pan
oven
whisk
baking pan
Directions
Melt 1 tbsp of the butter in a saucepan.
Whisk in flour and salt. Gradually whisk in milk until smooth. Bring mixture to a simmer over medium heat, stirring constantly, until slightly thickened.
Remove from heat.
Add 1-1/4 cups of the cheese, stirring until melted. Set aside.
Melt remaining 2 tbsp butter in a large frying pan.
Add mushrooms and onion; saute until tender and liquid evaporates.
Whisk eggs.
Add eggs and bacon or ham to mushroom/onion mixture. Cook until eggs are just set but still a little wet. Stir cheese sauce into egg mixture.
Spoon mixture into a greased 9-inch (23 cm) square baking pan or 2.5 L casserole.
Sprinkle remaining 1/2 cup cheese over top. Cover and refrigerate overnight.
The next morning, uncover and bake in a preheated 350 degrees F (180 degrees C) oven until heated through and cheese is melted, 20 to 25 minutes.