Directions:

Preheat oven to 450 degrees F

Cook the bacon in a 9-inch cast iron skillet over medium-low heat. When bacon is crispy, remove it from the pan, drain on paper towels and set aside. When bacon is cool, chop or crumble into small pieces.

Discard all but 1 tablespoon of bacon fat and return skillet to the stove top. Add onion and green pepper and cook over medium heat for about 3 minutes.

Turn off the heat leaving the skillet on the stove top. Add the spinach pieces and stir until the leaves begin to wilt, about 1 minute. Set skillet aside.

In a medium bowl, whisk the eggs, milk, butter, salt and pepper until frothy.

Pour the egg mixture into the skillet with the cooked onion, green pepper and spinach; add the bacon. Stir to distribute the ingredients evenly.

Turn the heat back to medium and cook egg mixture for about 5 minutes or until the egg begins to set. Do not stir.

Sprinkle the grated cheese evenly across the top and transfer the skillet to the oven. Bake 10 to 15 minutes or until a knife inserted near the center of the frittata comes out clean.