Season steaks on both sides with salt, pepper and butter. Put onto a hot grill and brown on both sides.
In a Dutch oven or cast iron fry pan, add 1/2 stick of butter, onions, mushrooms and salt. Place lid on top and allow them to sweat.
Add beer and place steaks in pan. Allow to stew until tender.
Combine the thyme, parsley, nutmeg, remaining butter and flour together. Use this to thicken the sauce so as to be able to coat the back of a spoon.