Whisk eggs lightly in a bowl

Add salt and pepper to taste

Add milk and mix through, then set aside

Slice mushrooms

Slice cold roast potatoes. I use leftover roast potatoes but if you don't have any you could fry up a couple of sliced potatoes before you start making the frittata. Or leave out the potatoes and add in another vegetable instead, like sliced peppers

Heat butter in a pan at a medium heat

When butter is sizzling add the mushrooms and the potatoes and allow to cook gently for a few minutes.

Pour the egg mixture over the vegetables in the pan and swirl gently so that the egg runs underneath.

Keep lifting the edges of the egg with a spatula so that the unset egg on top can run underneath. If you tilt the pan the egg will easily run underneath.

When the egg is almost set, add the feta cheese and the grated parmesan if using.

Finish off with a good scattering of chopped parsley. You can of course add other herbs if you wish such as chopped chives.

Serve at once or allow to cool and serve at room temperature.

A green salad and a slice of sourdough would go very well with this dish and also make it more substantial.