Preheat oven to 375 degrees F (190 degrees C).
Sauté the onion and garlic, in 1 tablespoon of coconut oil for about 5 minutes until soft.
Remove from pan and place in a bowl.
Add sliced sausages to the pan and stir gently until just cooked through.
Remove sausages from pan and set aside.
Add potatoes to the pan with some hot water and allow to steam for around 5 minutes until partially cooked, then remove from heat and drain off the water.
In a 9x13 pan or glass ovenproof dish, that is greased with coconut oil, layer the potatoes or butternut and sprinkle with a bit of salt and pepper.
Add the sausage and onion/garlic mixture and spread over the potatoes evenly.
Sprinkle the chopped parsley or cilantro over the layers in the dish.
In a large mixing bowl beat the eggs and milk together until well blended.
Add 1 cup of grated cheese to the egg mixture, stir to combine, and pour over the sausage layer. The egg/milk mix will run into the crevices between the rest of the ingredients leaving the majority of the cheese at the top.
Bake for about 40 minutes until golden and bubbly, keeping an eye on the frittata towards the end of the cooking time as you don’t want it getting too brown.