Pre-heat the oven to 425° F.
Par-bake the pie crust: Place the pie dough in the pie dish. Now, line with parchment paper. Add weights, or 1 cup dried beans, or, 1 cup dried rice on top. Bake for 15 minutes.
Meanwhile, layer one (or two, if needed) baking sheets with paper towels. Place the sliced tomaotes on the paper towels and sprinkle salt over the tops of the tomaotes.
Remove the pie from the oven, and discard the parchment paper and weights. Let cool completely.
Reduce the oven to 350° F.
On a separate baking sheet with a rack, place all but 3 of the tomaotes and roast in the oven for 40 to 45 minutes. Hold the 3 tomatoes for topping the pie after assembling.
Meanwhile, heat a medium-sized skillet over medium-high heat. Add the bacon and cook until just starting to crisp and grease is being rendered.
Add the chopped onion and cook until transluscent, about 4 to 5 more minutes. Use a slotted spoon to transfer to a plate lined with paper towels. Set aside.
Once the tomatoes are done roasting, remove from the oven and let cool for at least 20 minutes, still on the rack(s).
Make the filling by mixing together in a medium bowl the mayonaisse, cooked bacon / onion mixture, Dijon mustard, egg, and both cheeses. Stir until completely combined.
Add a thin layer of the filling to the par-baked pie crust. Use a knife to spread the filling.
Next, using a spatula, carefully add a layer of the roasted tomatoes. Sprinkle freshly ground black pepper over the tomatoes.
Now, sprinkle half the fresh basil and fresh oregano on top of the tomatoes.
Repeat this layering of filling, tomatoes, pepper and herbs. Add one more layer of the filling on top. Sprinkle more shredded cheese to cover any gaps.
Add the three remaining tomatoes on top and sprinkle on a little more of the herbs.
Bake for 40 minutes, until bubbly and lightly browned on top.
Let rest for 1 hour (if served sooner, the filling will still be somewhat fluid). Serve warm or at room temperature.