Quick self crusting quiche

This was passed onto me by my past supervisor "Mrs P" and is perfect when you want quick & easy!

4 eggs
1/2 cup flour
4oz melted butter
2 cup milk
1/4 tsp baking powder

Beat all together & then add:

1 small tin tuna (or salmon)
1 small sliced onion (I prefer red or a few spring onions chopped)
chopped parsley
1/4 cup grated cheese

Bake at 350oF for 40 minutes