01 -
Preheat the oven to 350°F and allow it to reach temperature while preparing the other components.
02 -
In a medium skillet, cook the thinly sliced onion in reserved bacon fat over medium heat until softened and caramelized, about 10 minutes. Set aside to cool.
03 -
Arrange half of the sautéed onions in the pre-baked pie shell, layer with half the tomato slices, and sprinkle with half the chopped bacon. Repeat with remaining onions, tomatoes, and bacon to complete the layers.
04 -
In a mixing bowl, combine shredded mozzarella, mayonnaise, sour cream, flour, garlic powder, salt, and black pepper. Mix thoroughly until uniform.
05 -
Spread the cheese mixture evenly over the layered filling. Place the filled pie shell on a baking sheet and bake for 35 to 40 minutes, or until the top is bubbly and golden brown.
06 -
Remove from the oven and allow the pie to cool for several minutes. Garnish with fresh parsley or chives before slicing and serving, if desired.