Preheat oven to 375 degrees Fahrenheit or 190 degrees Celsius, and place your baking rack on the bottom slot of your oven.

Unroll your pie crust or pâte brisée and press it gently into a 9-inch pie plate or tart pan. If your crust comes on a sheet of parchment paper, just leave it on the paper when you fit it into the pan. If your crust does not come on a sheet of parchment, and you want to be able to remove your quiche from its pan before serving, try spraying the pan with just a touch of nonstick baking spray before lining it with the crust.

Trim off any excess parchment and any dough that is more than an inch past the edge of the pan.

Fold the edges of the crust back and under so that you form a border at the top that is just taller than the edge of the pan, but is not folded over the pan edge (otherwise it will break off when you serve the quiche).

Next, use a fork to prick the crust all over the bottom—this will make sure the bottom doesn’t puff up as it bakes.

Line the crust with parchment paper or aluminum foil and cover with pie weights, raw rice, or dried beans.

Bake on the bottom oven rack for 20 minutes, then remove the parchment and weights. The edges of the crust should be golden, but the bottom will still look a little raw.

Bake for an additional 5 minutes, until the bottom dough no longer looks raw.

Meanwhile, while the crust is baking, chop spinach and sun-dried tomatoes and put in a medium bowl.

Slice mushrooms (cut in half as well if they are large), and mince garlic clove.

Then heat 1 tablespoon of olive oil in a medium skillet over medium-high heat.

Add sliced mushrooms and sauté until they lose their moisture and start to brown, stirring frequently, about 8 min. Season with salt and pepper while cooking.

Add garlic clove and sauté for 1 minute.

Remove from heat and add to the bowl with the spinach and sun-dried tomatoes.

In a different bowl, whisk together eggs, cream, mustard, salt, and pepper.

When crust has been removed from oven, spread the spinach-mushroom filling over the crust, then sprinkle the feta cheese over it.

Pour in the egg mixture.

Bake for 25-30 minutes on the bottom oven rack, or until the egg custard is cooked through and lightly browned on top. The filling should be completely set—if it jiggles when you touch the pan, it’s not done.

Wait to slice the quiche for at least 10-20 minutes—this will allow the quiche to fully set, and you’ll get cleaner slices. Serve either warm or at room temperature.