Heat the tablespoons of unsalted butter in a skillet over medium heat.
Add the onions and garlic and sauté until translucent.
Place the sliced mushrooms in the pan and brown for 5 minutes, stirring occasionally.
Pour in the broth and white wine and cook for 3 minutes.
Add the cream, mustard, worcestershire sauce, garlic, salt, pepper, parsley, thyme, marjoram and bay.
Bring to a gentle boil.
Lower the heat and simmer for several minutes.
In a small, separate bowl, mix the remaining 2 tablespoons of cream with 2 tablespoons of flour.
Add the flour slurry to the mushroom mixture and bring to a boil, stirring to avoid clumps.
Add the fresh chopped parsley.
Season with salt and freshly ground pepper.
Turn off the heat and cover the pan with aluminum foil to keep warm while cutlets are cooked.