Preheat oven to moderate. Oil ramekins. Boil, steam or microwave 2 medium peeled potatoes, until just tender; drain. Meanwhile, whisk 10 eggs, ½ cup of low fat milk and 1 cup of parmesan and ½ of cheddar cheese in large jug. Layer a few potato slices in each ramekin; top with rocket, chopped tomato, mushroom and basil. Carefully pour egg mixture over vegetables in pan. Bake frittata, covered, in moderate oven 45 minutes. Serve with toasted english muffins.