Heat the butter in a pan and add the onions once the butter has melted. Fry the onions low and slow till they get a nice colour on them.
Once that happens add in the ground beef. Season with salt, pepper, dried oregano and some dried chilli flakes.
Add in the mushrooms and continue cooking till the mixture starts to dry out. You want to cook out all the moisture from the ingredients so that when it cooks with the frittata it doesn’t release any moisture.
Once you are done cooking, turn off the heat and add in the cream cheese and mix well. Then just let it cool down.
Pre-heat your oven to 175C
Crack the eggs in a bowl and season with salt and pepper. Then add in the heavy whipping cream and the beef mixture once it’s cooled down and give everything a good mix.
Grease an oven proof dish with some butter and then pour in the frittata mixture.
Top with the mozzarella cheese and pepperoni slices and bake in the oven for 15 minutes till it’s cooked all the way through. The broil on a higher temp for about 4-5 minutes till the top is nice and golden brown.