Spinach, Mushroom, and White Bean Frittata

Ingredients for four servings

Use a 10-inch oven-safe skillet with sides at least 2 inches high. Weigh the beans after cooking and draining, and weigh the eggs without their shells.

• 8 large eggs, about 400 g out of their shells
• 240 g cooked navy beans with no added salt, drained
• 225 g raw white mushrooms, sliced
• 150 g raw spinach, roughly chopped
• 100 g yellow onion, diced
• 14 g olive oil (1 tablespoon), divided
• 56 g low-moisture part-skim mozzarella, shredded
• 1.5 g fine salt (about 1/4 teaspoon)
• 1 g ground black pepper (about 1/2 teaspoon)

Cook the frittata

Heat the oven to 375 °F with a rack in the center. A wider pan makes a thinner frittata that cooks sooner, while a smaller pan makes a deeper one that needs more time. Use a thermometer rather than relying only on the clock.

1. Coat the bottom and sides of a 10-inch oven-safe skillet with about 1/2 teaspoon of the measured oil. Heat the remaining oil over medium heat.
2. Add the onion and mushrooms. Cook for 8 to 10 minutes, stirring occasionally, until the onion is soft and the liquid released by the mushrooms has evaporated.
3. Add the spinach and cook for 1 to 2 minutes, just until wilted. Stir in the drained beans and spread the filling evenly across the skillet.
4. Whisk the eggs, salt, and black pepper in a bowl until no separate streaks of white remain. Pour the mixture over the vegetables and beans, then sprinkle the mozzarella evenly on top.
5. Cook without stirring for 2 minutes, until the edge begins to set. Transfer the skillet to the oven and bake for 10 to 14 minutes.
6. Check the center in two places with a food thermometer, without touching the pan. An egg dish is done when the center reaches 160 °F. Rest for 5 minutes, then cut into four equal wedges.

Estimated nutrition per serving

Estimated per serving, one quarter of the frittata: 330 calories, 24 g protein, 23 g carbohydrate, 17 g fat, 8 g fiber, and 420 mg sodium.

The calculation uses USDA FoodData Central values for 400 g raw whole egg, 240 g navy beans cooked without salt, raw spinach, raw white mushrooms, raw onion, olive oil, low-moisture part-skim mozzarella, black pepper, and 1.5 g salt. It counts all 14 g of oil and divides the full batch by four. Egg size, cheese brands, bean draining, substitutions, oil left in the pan, and the final cooked yield can change the result, so use these numbers as an estimate.

Pan size and allergen notes

In a 12-inch skillet, the egg layer will be thinner, so begin checking several minutes early. Do not crowd the full batch into an 8-inch skillet. Divide it between two suitable pans or use a 9-inch pie plate, because a deeper center takes longer to reach 160 °F. If you use a pie plate, coat it with the reserved oil, transfer the cooked filling, add the eggs and cheese, and begin checking after 15 minutes.

This recipe is vegetarian and contains egg and milk. The eggs are an egg allergen, and the mozzarella is a milk allergen. Check the labels on packaged beans and cheese if formulation or cross-contact matters for the people eating.

Cool, store, and reheat leftovers

Refrigerate leftover wedges within 2 hours of cooking. Put them in a shallow covered container and keep the refrigerator at 40 °F or below. Use refrigerated frittata within 3 to 4 days.

For best quality, wrap individual wedges and freeze them for up to 2 months. USDA cold-storage guidance gives leftover omelets, quiche, and egg casseroles a 2-month freezer window. The spinach and mushrooms can make a thawed wedge softer, so thaw it in the refrigerator and expect a little extra moisture.

Reheat only the amount you plan to eat. Heat each wedge until the center reaches 165 °F, checking with a food thermometer.

Questions

Sources

• USDA FoodData Central
• Dietary Guidelines for Americans, 2025-2030
• FoodSafety.gov, Safe Minimum Internal Temperatures
• USDA FSIS, Leftovers and Food Safety
• USDA FSIS, Keep Food Safe! Food Safety Basics