Step 1

Preheat oven to 425 degrees F and cook tater tots in a 9x13 dish until golden brown according to package instructions.

Step 2

Meanwhile, cook sausage with pepper, mushrooms, and onion in a large saute pan over medium heat until crumbly, about 20 minutes. Remove from heat and allow to cool.

Step 3

In a large bowl, whisk together eggs, milk, and ground mustard. Add cooked sausage mixture as well as half the cheese. Stir to combine.

Step 4

To bake, reduce oven temperature to 350 degrees F.

Step 5

Pour egg and sausage mixture over tater tots and top with remaining cheese. Cover with aluminium foil and cook for 40-45 minutes until eggs have set, allowing casserole to cook uncovered for last 5-10 minutes so that the top turns golden brown. Serve hot.