Preheat your oven to 375°F (190°C). Roll out your pie crust and place it in a 9-inch pie dish. Blind-bake for 8-10 minutes until golden.

Cook the thick-cut bacon in a skillet over medium heat until crispy, about 6-8 minutes. Crumble and reserve 1 tablespoon of drippings.

Add sliced onions to the skillet with the reserved drippings and cook gently for 10-15 minutes until soft and golden.

Slice firm tomatoes and sprinkle with salt. Let them sit on paper towels for 5 minutes to draw out moisture.

Layer half of the crumbled bacon, half of the onions, and one layer of tomato slices in the pre-baked crust. Repeat with remaining ingredients.

In a mixing bowl, combine mayonnaise, cheddar, mozzarella, fresh basil, salt, and pepper. Mix well and spread over the layered filling.

Bake in the oven for 30-35 minutes until the cheese is bubbly and golden brown on top.

Remove from oven and let cool for 10 minutes. Serve warm and enjoy!