Preheat oven to 180 degrees.
Line a baking tray with baking paper and place mushrooms and whole tomatoes on tray, drizzle with olive oil, salt and pepper and mix with your hands to ensure good coverage. (Tip: Oaky Creek Garlic & Rosemary Salt is also great here). Place in oven and cook for 25 minutes. Remove from oven and leave to cool. Line a baking tin with baking paper or grease an oven proof dish with olive oil or butter. Break eggs into a large bowl and add cream and salt and pepper to taste. Whisk well to combine. Add mushrooms, tomatoes, parsley and grated cheese and mix well. Pour into baking tin and bake for 25-30 minutes until frittata is puffed and golden.