Follow these simple and detailed instructions to create a perfectly cooked and flavorful Spinach Mushroom Frittata every time. Don’t be intimidated – this recipe is easier than you think!

Step 1: Prepare the Vegetables

• Mushroom Prep: Begin by cleaning your mushrooms. For button or cremini mushrooms, you can gently wipe them clean with a damp paper towel or mushroom brush to remove any dirt. Avoid soaking them in water, as they can absorb moisture and become soggy. Slice the mushrooms into even slices, about ¼ inch thick. This ensures they cook evenly and release their delicious earthy flavor.
• Onion and Garlic Prep: Peel and finely chop the onion. Mince the garlic cloves. Having these aromatics prepped and ready to go will streamline the cooking process.
• Spinach Prep: Wash the fresh spinach thoroughly and roughly chop it. If using frozen spinach, ensure it is completely thawed and squeeze out as much excess water as possible. Excess moisture can make the frittata watery.

Step 2: Sauté the Aromatics and Mushrooms

• Heat the Pan: Place an oven-safe skillet (cast iron or stainless steel, about 10-12 inches in diameter) over medium heat. Add olive oil to the pan and let it heat up until it shimmers slightly. This indicates the pan is hot enough for sautéing.
• Sauté Onion and Garlic: Add the chopped onion to the hot skillet and sauté for 3-5 minutes, or until softened and translucent. Stir occasionally to prevent burning. Once the onion is softened, add the minced garlic and cook for another minute until fragrant. Be careful not to burn the garlic, as it can become bitter.
• Sauté Mushrooms: Add the sliced mushrooms to the skillet with the onions and garlic. Increase the heat slightly to medium-high. Cook the mushrooms, stirring occasionally, until they release their moisture and begin to brown. This process usually takes about 8-10 minutes. Don’t overcrowd the pan with mushrooms, as this will cause them to steam rather than brown. If you have a lot of mushrooms, you may need to sauté them in batches. Season the mushroom mixture with a pinch of salt and pepper while cooking to enhance their flavor.

Step 3: Wilt the Spinach

• Add Spinach to the Pan: Once the mushrooms are nicely browned and softened, add the chopped spinach to the skillet. Cook, stirring frequently, until the spinach wilts and reduces in volume. This should only take a couple of minutes. The heat from the pan and the moisture from the vegetables will quickly wilt the spinach.
• Remove from Heat: Once the spinach is wilted, remove the skillet from the heat and set aside. Allow the vegetable mixture to cool slightly while you prepare the egg mixture.

Step 4: Prepare the Egg Mixture

• Whisk Eggs and Dairy: In a large mixing bowl, crack the eggs. Add the milk or cream, salt, and pepper. Whisk vigorously until the eggs and dairy are well combined and slightly frothy. Whisking incorporates air into the eggs, resulting in a lighter and fluffier frittata.
• Add Cheese and Herbs (Optional): Stir in the shredded cheese and any optional fresh herbs (like parsley or chives) into the egg mixture. Reserve a little cheese to sprinkle on top of the frittata before baking, if desired.

Step 5: Assemble and Bake the Frittata

• Combine Vegetables and Eggs: Pour the egg mixture evenly over the sautéed vegetables in the skillet. Use a spatula or spoon to gently distribute the vegetables throughout the egg mixture, ensuring they are evenly dispersed.
• Optional Toppings: If desired, sprinkle the reserved cheese and any other toppings (like red pepper flakes or sun-dried tomatoes) evenly over the top of the frittata.
• Bake in Oven: Preheat oven to 375°F (190°C). Place the skillet in the preheated oven and bake for 20-25 minutes, or until the frittata is set and lightly golden brown on top. The frittata is done when it is puffed up and the center is no longer jiggly. You can insert a knife into the center; it should come out clean when the frittata is cooked through.
• Broil for Golden Top (Optional): For a more golden brown top, you can broil the frittata for the last 1-2 minutes of baking. Watch it closely to prevent burning.

Step 6: Cool and Serve

• Cool Slightly: Remove the frittata from the oven and let it cool in the skillet for a few minutes before slicing and serving. This allows the frittata to set further and makes it easier to slice.
• Serve Warm: Slice the Spinach Mushroom Frittata into wedges and serve warm. It’s delicious on its own or with your favorite sides.