Heat a pan on the stove and add the olive oil and butter; once the butter is melted, add onion and garlic and sauté until soft, about 15 minutes.

Add in the chopped mushrooms, dried thyme, salt and pepper, and let cook until soft and browned, about 10 minutes.

Remove the cooked onions, garlic and mushrooms and set aside.

Add chicken broth and wine to the pan and bring to boil and cook until liquid is reduced by half.

Reduce heat to low and add the onions, garlic and mushrooms back to the pan. Meanwhile, in a small bowl, mix together the flour and Greek yogurt. Add Greek yogurt and flour mixture to the pan and continue to cook over low heat until the mixture thickens.

Season with salt and pepper to taste.

Serve over pasta or egg noodles.