Add 2 tablespoons of butter and the oil to a large skillet over medium heat.
Fry the onions in a skillet until well softened. Set aside.
Add more butter and oil if needed and fry the cooked spaetzle until slightly browned, about 2 to 3 minutes.
Remove from the pan to a serving platter and set aside while you cook the mushrooms.
Set the skillet back over high heat and add a little more olive oil and remaining 2 tablespoons of butter. Add the thyme, mushrooms and garlic and saute until golden brown, about 4 to 5 minutes.
Season with salt and pepper, to taste.
Add the cream and mustard and stir well.
Reduce the mixture until the sauce is nice and thick, about 3 minutes.
Fold in the spaetzle.
Transfer to a serving bowl, garnish with chives and serve with pork schnitzel or chops.
