Cook the bacon and sausage in a 10-inch cast-iron skillet over medium heat until the bacon is crisp and the sausage is cooked.
Add the scallions, sliced mushrooms, and serranos and cook for a few minutes. Toss in spinach and garlic and cook a couple minutes longer.
Whisk the eggs, heavy cream, salt, and pepper in a large bowl. Stir in cheddar cheese. Pour the egg mixture over the other ingredients in the pan.
Bake for 15 minutes, or until slightly jiggly in the center. Don't overcook.
Remove the pan from the oven and cool slightly before serving. Garnish with chopped parsley if desired.
Notes
If there is an excess amount of bacon grease, drain most of it, before adding the eggs to the pan.
Don't over mix the eggs. This can incorporate too much air into the eggs which will cause the Frittata to puff up and eventually collapse. As a result, the Frittata will end up dense instead of light and fluffy.
This Keto Frittata freezes well in an airtight container, for up to a few months.
To reheat frozen Frittata, defrost in the fridge overnight and then reheat in a 350-degree F. oven for approximately 5 minutes.
Frozen Frittata becomes soggy and rubbery if reheated in the microwave so if possible, use the oven.
Frittatas aren't just for breakfast. They are filling enough to be served for lunch or dinner.