Mushroom and Spinach Frittata

A fluffy, savory breakfast frittata packed with golden sautéed mushrooms, tender spinach, and a gently set, custardy egg center.

Ingredients

• 8 large eggs
• 2 cups mushrooms, sliced (about 8 oz / 225g)
• 3 packed cups baby spinach (about 3 oz / 85g)
• 1/3 cup milk (or water in a pinch)
• 1/2 cup shredded cheese (cheddar, mozzarella, or any melting cheese)
• 1/4 cup grated parmesan (optional but excellent)
• 1/2 small onion, finely diced (optional)
• 1 clove garlic, minced (optional)
• 2 tbsp olive oil (or 1 tbsp oil + 1 tbsp butter)
• 3/4 tsp kosher salt (or 1/2 tsp fine salt), plus more to taste
• 1/2 tsp black pepper
• 1/2 tsp dried oregano or thyme (optional)
• Pinch of chili flakes (optional)

Method

• 1

  Step 1: Prep the oven + eggs

  Heat oven to **400°F / 200°C**. In a bowl, whisk **eggs, milk, salt, pepper**, and **oregano/thyme** (if using) until well combined and slightly foamy. Stir in the **shredded cheese** (hold back a tablespoon for the top if you like).

• 2

  Step 2: Brown the mushrooms (flavor step)

  Heat **olive oil** in a **10-inch / 25cm oven-safe skillet** over **medium-high** heat. Add mushrooms and cook, stirring occasionally, until they release their liquid and it evaporates, then continue cooking until **deep golden** in spots, **6–8 minutes**.

• 3

  Step 3: Sauté aromatics + wilt spinach

  Add onion (if using) and cook until softened, **2 minutes**. Add garlic (if using) and stir until fragrant, **30 seconds**. Add spinach and cook just until **wilted**, **30–60 seconds**. Season with a tiny pinch of salt if needed.

• 4

  Step 4: Add eggs + gently set edges

  Reduce heat to **medium-low**. Give the egg mixture a quick whisk again, then pour into the skillet. Use a spatula to gently nudge the mushrooms/spinach so they’re evenly distributed. Cook **2–3 minutes** until the edges look set but the center is still quite wet. Sprinkle the reserved cheese and **parmesan** (if using) on top.

• 5

  Step 5: Bake until just set

  Transfer skillet to the oven and bake **8–12 minutes**, until the frittata is **puffed**, the center is **just set** (a slight wobble is perfect), and the top is lightly golden.

• 6

  Step 6: Rest + serve

  Rest in the pan **5 minutes**. Slice into wedges and serve warm.

Tips

• **No oven-safe skillet?** Cook in any pan, then transfer to a lightly oiled baking dish and bake until just set.
• **Make it extra fluffy:** Whisk eggs vigorously for 30 seconds to incorporate air; don’t skip the milk (or water).
• **Cheese options:** Feta is great with spinach; Swiss pairs beautifully with mushrooms.
• **Add-ins (keep it breakfast-friendly):** A handful of chopped herbs, or a pinch of smoked paprika for warmth.
• **Storage:** Refrigerate slices in an airtight container **up to 4 days**. Reheat gently in the microwave (20–40 seconds) or a covered skillet on low.
• **To serve:** Great with toast, a side of fresh fruit, or tucked into a warm tortilla as a breakfast wrap.

Nutrition (per serving, estimate)