Press your pie crust into the bottom and sides of a cold 10-inch cast-iron skillet. Prepare the edges of the crust as desired. Place the skillet and crust into the fridge for a minimum of 30 minutes.

Slice the tomatoes and squeeze out the seeds. Place the slices onto a paper towel and sprinkle them with 1/2 of the salt. Let them stand at room temperature for 30 minutes.

Preheat your oven to 425.

In a medium bowl, combine the cheeses, mayo, egg, herbs, pepper and remaining salt.

Remove the crust from the fridge and sprinkle with the red onion and then top with one-third of the cheese mixture.

Use a paper towel to remove any excess moisture from the tomatoes and layer half of them over the cheese mixture. Top with another one-third of the cheese, the remaining tomatoes and finish with the remaining cheese mixture.

Bake until golden brown for about 40 minutes. Allow to cool slightly before serving. This is also great served cold or at room temperature.