Flavorful roasted mushrooms top this tasty Italian omelet
Heat the oven to 425F degrees.
Place the sliced mushrooms in a medium bowl and sprinkle with 2 tablespoons olive oil. Stir to evenly coat the mushrooms with the oil.
Place the mushrooms in one layer on a parchment covered baking sheet.
Bake the mushrooms at 425F degrees for about 10 minutes. Then turn them over to bake the other side, continuing to bake them for 10-15 minutes until they are nicely browned.
Remove the mushrooms from the oven and set aside.
Using a 10-inch cast iron skillet, heat 2 tablespoons oil over medium heat until hot.
Add the onions and sauté until onions are soft.
Add the red peppers and zucchini and continue sautéing until the vegetables are soft.
While the vegetables are cooking, place the eggs in a medium bowl and whisk until emulsified.
Add the milk, salt, and pepper; whisk, and pour the egg mixture into the hot cast iron skillet.
Cook over medium heat until the egg mixture is nearly set.
Sprinkle the cheeses evenly over the top of the cooked eggs and vegetables.
Spread the roasted mushrooms evenly over the top of the frittata.
Place the skillet a couple of inches below the broiler element and broil on high until lightly browned (about 3-5 minutes).
Make Ahead: To save time in the morning, you can roast the mushrooms up to 3 days prior and refrigerate. Then just pull them out of the refrigerator and toss them on top just before broiling.