Season the cutlets with salt and pepper. In a pan, fry in some neutral oil over high heat for about 2 minutes per side – they should only be lightly browned. Remove them from the pan.
Clean the mushrooms and slice them. Finely dice the onion and garlic.
Fry the mushrooms in the cutlet pan until lightly browned. Add the onion and garlic and sauté until translucent.
Deglaze with white wine and broth and let it reduce briefly. Stir in the heavy cream, broth, and mustard and let everything simmer gently for 5 minutes. Season with salt and pepper.
Set the seared cutlets in a casserole dish and pour the mushroom sauce over them.
Sprinkle the cheese evenly over the top and bake the casserole for 20-25 minutes, or until the cheese is golden brown. Serve and enjoy!