Remove all packaging and bake the crust at 400° for 5 minutes. Transfer to a rimmed baking sheet, still in the foil pan, and set aside.
1 9" frozen deep dish pie crust
Add the oil to a small skillet set over medium heat. Add the veggies, stirring to combine, and saute just until softened.
1 tbsp extra virgin olive oil, 1/2 cup diced onion, 1 green bell pepper
Add the beef to the pie crust and spread out evenly in the bottom. Spread the sauteed veggies evenly out overtop, followed by half the cheese. Set aside.
1 3/4 - 2 cups roughly chopped deli roast beef, 2 cups shredded mozzarella cheese
Add the eggs, milk, steak sauce, and Italian seasoning to a small mixing bowl. Whisk them together to evenly combine, then pour the mixture evenly out into the crust. Sprinkle the remaining cheese evenly out overtop.
4 large eggs , 1/2 cup milk, 1 tbsp steak sauce, 1/4 tsp Italian seasoning
Bake at 375° for 25-35 minutes, just until the filling's puffed up and the center's set.
Carefully remove the hot quiche from the oven, and let it rest for 10 minutes.
Slice, serve warm, and enjoy!