2) Meanwhile, whisk the eggs, then stir in the ricotta, Gruyere, melted butter, salt, pepper and basil. Sprinkle on the flour and baking powder and stir into the egg mixture.
3) Pour the egg mixture over the potatoes and place the pan in the centre of the oven. Bake the frittata until it is browned and puffed, 50 minutes to 1 hour. It will be rounded and firm in the middle and a knife inserted in the frittata should come out clean. Serve hot.