Preheat the oven to 180°C conventional oven/ 160°C fan-forced (350° Fahrenheit/Gas 4). Grease a round baking dish with butter (alternatively, line a baking dish with baking paper).
Heat half of the olive oil in a medium-sized frying pan over medium heat. Add the onion, sliced potatoes and red pepper (capsicum). Cook, continuously stirring for 10 minutes or until the onions are golden and potatoes/peppers are just tender.
Use a fork to lightly whisk the eggs and milk together in a bowl until combined. Add the remaining olive oil, chopped parsley and season well with salt. Whisk until well combined.
Arrange the potato and capsicum mixture on the base of the baking dish. Arrange the provolone cheese over the potato and capsicum. Pour the egg mixture evenly over the potato and capsicum. Bake the frittata for 30 minutes.
Allow the Red pepper and potato frittata to cool for 5 minutes before serving – buon appetito.