Pre heat the oven to 190°c.
Cook the sausages and bacon medallions. You can do this in advance and keep them in the fridge until you're ready for them.
Arrange the sausage slices in the bottom of an 8 inch round silicone cake mould. Place the cooked bacon medallions on top, followed by the sliced mushrooms then the sliced tomatoes.
Crack the eggs into a large bowl or jug, add the quark and some salt and pepper, then whisk until they mixed well and there's no lumps or quark. Pour the eggs into the cake mould, then sprinkle the chopped parsley on top.
Cook at 190°C for 25 - 30 minutes, or until the quiche is set and golden in colour.