Set your oven to three hundred fifty degrees Fahrenheit or one hundred seventy five degrees Celsius so it is fully heated when you are ready to bake
Caramelize the Onions:
Cook sliced onions gently in a skillet over medium heat using a spoonful of the reserved bacon drippings let them soften and turn deep golden which takes about ten minutes this builds deep sweet flavor and takes away any sharpness cool slightly before using
Layer the Pie:
Arrange half the caramelized onions in the pre baked crust then add half the tomato slices and half the crumbled bacon repeat with the rest of the onions tomatoes and bacon for even flavor and texture in every bite
Prepare the Topping:
Mix shredded mozzarella mayonnaise sour cream flour garlic powder salt and black pepper in a bowl until smooth and fully combined be sure to mix well so there are no dry pockets
Top and Bake:
Spread the cheese topping evenly over your filled pie shell smoothing to the edges place the pie on a baking sheet to catch spillover and bake for about thirty five to forty minutes until the top is deep golden brown and bubbling and the edges are set
Cool and Garnish:
Let the pie rest for at least ten minutes so it slices cleanly and finishes setting sprinkle with fresh chopped chives or parsley if desired for extra color and flavor
