Ham and Cheese Breakfast Casserole

Ingredients:

• 8 large eggs
• 90 g butter + extra for greasing the pan
• 1 large onion, thinly sliced
• 4 cups bread, cut into 1 cm cubes (cut off crusts)
• 220 g of mushrooms, thinly sliced
• 1 and 1/4 cups light cream
• 1 teaspoon Dijon mustard
• A pinch of cayenne pepper
• 110 g diced ham
• 1.5 cups grated Gruyere, Emmental, or Jarlsberg cheese (about 110 g)
• 2 small plum tomatoes, very thinly sliced
• 2 tbsp. l. grated parmesan
• 2 tbsp chopped parsley, for serving

Preparation:

1. Preheat oven to 175°C and grease a 22 x 32 cm baking dish with butter.
2. Heat 2 tablespoons of butter in a large skillet over medium-high heat. Add the onion and cook, stirring occasionally, until lightly browned, about 5 minutes. Reduce the heat to medium and continue cooking and stirring until the onion is soft and golden, about 20 minutes more. If it starts to burn, reduce the heat further. Season with salt and pepper to taste.
3. Meanwhile, heat another large skillet over medium heat. Add 2 tablespoons of butter and the bread and cook, stirring occasionally, until golden brown, about 8 minutes. Season with salt and pepper to taste. Transfer the bread to a large bowl. Increase the heat to medium-high, add the remaining 2 tablespoons of butter and the mushrooms and cook, without stirring, until golden brown, about 1 minute. Continue cooking, stirring occasionally, until softened, about 2 more minutes. Season with salt and pepper to taste.
4. In a large bowl, combine the eggs, cream, mustard, cayenne pepper, 1/2 teaspoon salt, and a pinch of freshly ground black pepper. Add the onion, bread, mushrooms, ham, and 1 cup of Gruyere. Transfer the mixture to a greased baking dish. Top with a single layer of tomatoes and sprinkle with the remaining 1/2 cup of Gruyere and Parmesan. The casserole can be refrigerated overnight and baked the next day.
5. Bake until the top is golden brown and the casserole is set (it shouldn't jiggle when shaken), about 40 minutes. Sprinkle with parsley and serve.