Preheat oven to 350°F (175°C).

Bake the pie crust for about 15 minutes to pre-bake.

If using frozen broccoli, cook it until tender-crisp. Chop into bite-size chunks.

If using frozen spinach, thaw and drain thoroughly to remove excess moisture.

Place the broccoli or spinach in the bottom of the pre-baked pie crust.

In a separate bowl, whisk together the eggs and whipping cream until well combined.

Stir in the Swiss cheese, Monterey Jack cheese, and cheddar cheese.

Add the optional drained mushrooms.

If using shrimp or crab, chop it and add it to the egg mixture.

Pour the egg mixture over the broccoli or spinach in the pie crust.

Bake for 30 to 35 minutes, or until a knife inserted into the center comes out clean and the quiche is set and golden brown.