Easy Asparagus and Mushroom Frittata

Preheat oven to 170 C / Gas mark 3.

Melt butter in an oven-safe frying pan over medium heat. Stir in olive oil and asparagus, and cook until the asparagus is tender, about 10 minutes. Stir in the mushrooms, and continue cooking about 5 minutes.

In a medium bowl, whisk together eggs, water and thyme. Pour into the pan, and reduce heat to low. Cover, and cook 5 minutes.

Transfer the pan to the preheated oven. Bake 10 to 15 minutes, until eggs are no longer runny. Top the mixture with Parmesan cheese and mozzarella cheese. Turn on the grill, and grill until cheeses are melted and lightly browned.