In a large mixing bowl, combine the flour and salt. Add the diced butter and use a pastry cutter or your fingers to mix until the mixture resembles coarse crumbs.

Gradually add ice water, 1 tablespoon at a time, mixing until the dough comes together.

Shape the dough into a ball, wrap in plastic wrap, and allow to chill in the refrigerator for 15 minutes, while you preheat the oven and work on the filling to save time.

Roll out the chilled dough on a floured surface to about 1/8-inch thickness.

Use a round cutter or a glass (about 3-4 inches in diameter) to cut circles from the dough. Press each circle into the cavities of a standard muffin tin, trimming any excess dough. Prick the bottoms with a fork.

Bake the crusts for 8 minutes, then set aside.

Heat the olive oil in a skillet over medium heat. Sauté the spinach for 2-3 minutes, until wilted. Add the sun-dried tomatoes, olives and feta cheese and remove from the heat.

In a large bowl, whisk together the eggs, milk, salt, and pepper.

Evenly divide the spinach filling among the pre-baked crusts in the muffin tin.

Follow with the egg mixture into each crust, filling just to the top but not overflowing.

Bake in the preheated oven for 20-25 minutes, or until the filling is set and the tops are lightly golden.

Let the mini quiches cool for 5 minutes in the tin before carefully removing them with a small knife or spatula.