Preheat oven to 375 degrees.
To create pie crust, pulse flour, salt and butter in a food processor until the mixture has a few coarse crumbles. Pulse and add water until the dough resembles large grains of wet sand.
On a lightly floured surface, turn out dough and form into a disk. Roll out dough to fit a 9" pie plate. Gently place dough into pie plate and fold over edges and crimp. Set aside.
Place 1 oz of crumbled feta on bottom of crust.
Arrange slices of tomato in a "fan" or "spiral" pattern. Don't get too precious about this, just make it kind of pretty.
Sprinkle with remaining feta.
Whisk three whole eggs into one cup whole milk. Season according to your preference.
Pour milk and egg mixture into pie plate, over tomatoes and cheese.
Place pie plate on a rimmed baking sheet and cook for 35-40 minutes, until the top is lightly golden, the edges are set and the center is just slightly wobbly.
Cool to room temperature (approximately 1-2 hours) slice and top with pesto if desired.