1. Preheat the oven to 390°F (200°C). Dice the bacon and set aside. Peel and chop the onion and garlic. Clean the mushrooms and set everything aside.

2. Heat up a large frying pan, add the diced bacon and fry until nicely browned. Remove from the pan and set aside – leave the fat in the pan. Add some butter and let it melt, then add the mushrooms and fry for 5-7 minutes until nicely browned. Add some more butter if needed, add the chopped onion and garlic and fry until soft and slightly browned. Deglaze with the wine and cook until the liquid is reduced to half of the amount. Add the heavy cream, mustard, and fresh thyme. Add the bacon back to the pan and mix everything. Season with salt and pepper, reduce the heat and let simmer until the sauce has thickened a bit – about 4-5 minutes. If the sauce thickens too much, add some water to thin it out again.

3. If your pan is good to go into the oven you can use it, otherwise, transfer the mushrooms to a casserole dish, sprinkle with the mozzarella and parmesan cheese, and place in the upper part of the oven to melt the cheeses and get a nice crust (about 3-5 minutes). Take out of the oven, sprinkle with the chopped parsley and serve with fried potatoes or some bread.