- Preheat oven to 400°F.
- Place the piecrust into the pan and pre-bake for 10 minutes. Set aside when finished.
- Thaw frozen cut spinach leaves and removes all excess moisture.
- Grate the cheddar cheese, dice the onion, and dice the ham.
- In a mixing bowl, combine the milk, eggs, mustard, salt, and pepper.
- In the partially baked crust, layer the ham, spinach, onions, and cheese; pour the milk mixture evenly over the cheese and meat mixture; then crumble the feta cheese on top, or use additional cheddar cheese and omit the feta.
- Reduce the heat of the oven to 350°. Place the quiche in the oven and bake for 55 to 60 minutes.
- To test for doneness, insert a knife in the center of the quiche. If the knife comes out clean, the quiche is done.
- Remove the quiche from the oven when done and let it stand 10 minutes before serving. Garnish with salsa.
Note: a combination of cheeses may be substituted, as well as different vegetables and meat.