Cook bacon in a large cast iron or oven-proof skillet until brown and crisp. Remove from pan and drain on paper towel.
Reserve 2 Tablespoons of bacon grease in skillet and sauté onion and garlic for about 2 minutes or until onion is soft.
Add in fresh spinach and chopped tomato and cook until spinach is wilted, about 2 minutes.
Whisk eggs with half and half and seasonings.
Stir in cooked, crumbled bacon and cheese.
Pour egg-cheese mixture over vegetables in skillet and let it continue to cook for 3-4 minutes or until eggs start to set at the edges.
Place skillet into preheated oven and cook for 10-15 minutes or until center is cooked through. I found that 10 minutes worked almost every time.
CAUTION: Remove pan carefully with potholder as the handle will be HOT!
TIPS FOR THE BEST FRITTATA
Precook vegetables as raw vegetables will release too much water and make the frittata soggy. The vegetable will also not cook in the time it takes to make the frittata which will result in raw vegetables.
Do not overbeat the eggs! This causes the eggs to fluff up too high during baking and fall after removing from the oven resulting in a very dense, somewhat tough egg frittata.
Use full-fat dairy for a creamier, less watery breakfast frittata. Heavy cream, half and half, whole milk, sour cream and yogurt will all work. 2% milk or skim milk will not.
Do not overcook this bacon frittata! Look for a slightly jiggly center when moving pan as well as a puffy exterior with opaque egg mixture.