Crustless Spinach Mushroom Quiche with Feta

This crustless spinach mushroom quiche puts sautéed mushrooms, wilted spinach, and feta into a tender egg custard without pastry. It is naturally lower in carbohydrates than a traditional quiche and works for breakfast, brunch, lunch, or a light dinner.

Cooking the mushrooms until their liquid evaporates is the most important step. It concentrates their flavor and prevents water from collecting under the eggs. The quiche slices best after a 10-minute rest and can be refrigerated for make-ahead meals.

Why this crustless quiche is not watery

Mushrooms contain a large amount of water. Let them cook in a wide skillet until the pan looks nearly dry and the edges begin to brown. Crowding a small pan steams the mushrooms, so use a 10- to 12-inch skillet and stir only occasionally.

Fresh spinach also releases moisture, but only needs a minute or two to wilt after the mushrooms are dry. Let the vegetables cool briefly before they meet the eggs; very hot vegetables can begin setting small pieces of egg in the mixing bowl.

Ingredient notes

Mushrooms

Cremini mushrooms have a slightly deeper flavor, while white button mushrooms are mild and usually economical. Slice them about 1/4 inch thick so they brown before becoming leathery. Do not rinse them in a bowl of water; wipe away soil or rinse quickly and dry thoroughly.

Spinach

Five ounces of fresh baby spinach looks bulky but wilts down quickly. Add it in two or three batches. For frozen spinach, thaw 5 ounces completely and squeeze it very dry in a clean towel, then stir it into the browned mushrooms just long enough to warm.

Feta and salt

Feta brings tang and salt, so the egg mixture needs only 1/4 teaspoon added salt. Block feta that you crumble yourself usually has a creamier texture than precrumbled cheese. Goat cheese, shredded Swiss, or sharp cheddar can replace it in the same volume, but sodium and flavor will change.

Milk

Whole or 2% milk makes a custard that is tender without being heavy. Skim milk works but yields a slightly firmer texture. Unsweetened plain dairy-free milk can be substituted, provided it has no vanilla or added sugar.

How to tell when crustless quiche is done

The outer two inches should look set and slightly puffed. The center may wobble gently as one piece but should not ripple like liquid. An instant-read thermometer in the center should register 160°F. The temperature continues to even out during the 10-minute rest.

A deeply browned top can signal that the quiche is overcooking, especially in a dark metal pan. If using metal rather than glass or ceramic, begin checking at 28 minutes. A shallow pie plate may also finish sooner than a deep dish.

Common questions

Can I make spinach mushroom quiche the night before?

Bake it fully, cool it promptly, cover, and refrigerate. Reheat the whole quiche loosely covered at 325°F until hot, or warm individual slices in the microwave. Do not leave a raw egg mixture assembled overnight with warm vegetables.

Why did my quiche shrink?

Some deflation is normal as steam escapes. Vigorous whisking can incorporate excess air and cause a dramatic rise followed by more shrinking. Whisk only until the whites and yolks are blended, and avoid baking beyond 160°F in the center.

Can I use egg whites?

Replace up to four whole eggs with 1/2 cup liquid egg whites. Using only whites produces a firmer, less rich texture and may cook a few minutes faster. Keep the milk and vegetable amounts unchanged.

Is crustless quiche gluten-free?

This ingredient list contains no wheat-based crust or flour. Check the labels on feta, cooking spray, and any added seasonings when cooking for someone who requires certified gluten-free ingredients, because manufacturing practices vary.

Can I freeze the quiche?

Yes. Cool it completely, cut into slices, wrap each slice, and freeze in an airtight container for up to 2 months. Thaw overnight in the refrigerator before reheating. Freezing can make the custard release a small amount of water, but individual slices reheat evenly.

Variations

• Ham and spinach: Replace half of the mushrooms with 1 cup diced cooked ham and reduce added salt.
• Broccoli-cheddar: Use 1 1/2 cups finely chopped cooked broccoli instead of spinach and feta.
• Sun-dried tomato: Add 1/3 cup drained, chopped oil-packed sun-dried tomatoes with the spinach.
• Herb-forward: Add 2 tablespoons chopped parsley or 1 tablespoon chopped fresh dill to the egg mixture.

Storage and reheating

Refrigerate the quiche in a covered container within 2 hours and use it within 3 to 4 days. Reheat leftovers to 165°F. For meal prep, pack slices only after they are completely cool so condensation does not collect inside the container.

Serve warm or at room temperature for no more than 2 hours. Pair a slice with fruit for breakfast or a green salad for lunch. For another make-ahead egg breakfast, see the make-ahead sausage and egg breakfast casserole. The cottage cheese egg salad without mayo is a separate chilled lunch option.