Step 1

Parbake the crust: Preheat the oven to 350 degrees F. Remove the dough from the refrigerator and place it on a well-floured surface. Working from the center, roll the dough into a 12-inch circle, then transfer it to an ungreased 9″ pie dish. With a fork, pierce rows of holes in the bottom and sides of the dough, about 1 inch apart. Bake until the crust is lightly golden, 10 to 15 minutes. Set aside to cool.

Step 2

Prepare the filling: Heat the olive oil in a large skillet over medium-high heat. Add the leeks and sauté for 5 minutes, until tender. Add the spinach and sauté for 2 minutes. Remove from heat and set aside.

Step 3

In a large bowl, whisk together the eggs, egg whites, milk, Greek yogurt, salt, and pepper. Set aside.

Step 4

Spoon the spinach and leek mixture into the bottom of the crust, then sprinkle the feta over the top.

Step 5

Gently pour in the egg mixture.

Step 6

Bake the quiche for 45 to 55 minutes, until eggs are set in the center and puffed slightly and the crust is golden brown. Let the quiche cool on a wire rack for 10 minutes. Slice and serve warm or at room temperature.