01 -
Preheat oven to 350°F while preparing the filling.
02 -
Cook bacon slices in a medium skillet over medium heat until crispy, about 6-8 minutes. Remove and drain on paper towels, reserving 2-3 tablespoons of rendered fat. Chop cooled bacon into bite-sized pieces.
03 -
Add thinly sliced onions to the skillet with reserved bacon fat. Cook over medium heat, stirring occasionally until onions are soft, golden, and caramelized, about 10-12 minutes. Remove from heat and cool slightly.
04 -
Spread half the caramelized onions evenly over the pre-baked pie shell. Layer half the tomato slices over the onions in an overlapping pattern. Sprinkle half the chopped bacon over tomatoes. Repeat layers with remaining onions, tomatoes, and bacon.
05 -
In a bowl, combine shredded mozzarella, mayonnaise, sour cream, flour, garlic powder, salt, and pepper. Mix thoroughly until smooth and creamy.
06 -
Spread the cheese mixture evenly over the layered filling, covering to the edges of crust. Place pie on a rimmed baking sheet and bake for 35-40 minutes until the top is golden brown and bubbly.
07 -
Allow pie to cool 10-15 minutes before slicing. Optionally, sprinkle with fresh parsley or chives before serving.