Place the pie crust in a greased 9" pie pan. Press the pie crust evenly over the pie plate. Crimp or fold the edges of the crust around the outside.

Using a medium skillet, heat the oil and add the onion. Sauté until the onion begins to brown.

Spread the onions over the pie crust bottom.

Sprinkle ⅓ of the cheese over the onions.

Sprinkle ⅓ of the basil leaves over the cheese.

Slice the tomatoes and place ⅓ of them in a single layer over the basil and cheese.

Add ⅓ of the cheese, sprinkled over the top of the tomatoes.

Repeat layers (except onions).

Pour the beaten eggs over the layers.

Sprinkle with salt and pepper.

Bake at 375°F for about 20 minutes, or until the eggs fully set.

Let rest for 5 minutes before serving. The quiche can be served hot or at room temperature.