• Preheat your oven to 375°F. Grease a 9x12-inch baking dish (an oval dish works, but will produce a thicker casserole).
• In a medium skillet, cook pancetta, bacon, or sausage over medium-high heat until browned and the fat has rendered (about 3 minutes).
• Remove the meat and leave the fat in the pan. Add 1 to 2 tablespoons olive oil—more if using pancetta, less for bacon.
• Add onion, mushrooms, and salt. Stir, cover, and cook until the vegetables are soft (about 5 minutes). Let cool.
• In a large bowl, whisk the milk and eggs. Add pancake mix and whisk until smooth.
• Stir in the hash browns and about 6 ounces of cheese.
• Add the cooled meat and vegetables. Stir gently to combine.
• Pour into the prepared dish and sprinkle the remaining cheese on top.

Make Ahead Option

• Cover tightly and refrigerate overnight. Before baking, let it sit at room temperature for 10 minutes.

Bake

• Bake uncovered for 30 minutes, or until browned on top and firm in the center. Let rest for 5 minutes before slicing and serving.