- cooking spray (such as Pam®)
- 1 cup shredded Cheddar-Monterey Jack cheese blend
- 1 cup shredded mozzarella cheese
- 1/4 cup butter, divided
- 1/2 pound fresh mushrooms, sliced
- 6 green onions, sliced
- 2 cups fresh spinach
- 1/2 cup chopped tomatoes
- 12 eggs
- 1 cup half-and-half
- 1 teaspoon prepared yellow mustard
- 1 teaspoon dried marjoram
- 1 teaspoon dried tarragon
- ground black pepper to taste
- Preheat oven to 350 degrees F (175 degrees C). Spray a 9×13-inch baking dish with cooking spray.
- Layer Cheddar-Monterey Jack cheese blend and mozzarella cheese in the prepared baking dish.
- Heat 2 tablespoons butter in a large skillet over medium-high heat; saute mushrooms and green onions until mushrooms are golden brown, 5 to 10 minutes. Add spinach and tomatoes; saute just until spinach wilts, 3 to 5 minutes. Spoon vegetable mixture over cheese mixture.
- Whisk eggs, half-and-half, mustard, marjoram, tarragon, and black pepper together in a bowl; pour over vegetable mixture. Dot remaining butter on the egg mixture.
- Bake in the preheated oven until a knife inserted near the center comes out clean, 35 to 45 minutes. Let stand 5 minutes before serving.