Wagner's Mustards are amazing! Bob makes all his mustard here in the Treasure Valley, you can learn more about Wagner's Mustards here. We love being able to sell his mustards in our store. This recipe is on his website as well.
Place olive oil and butter in a small sauté pan over medium high heat. Add garlic and pan roast until soft, about 5 -10 minutes. Let cool. Remove the garlic and reserve the oil/butter. Add garlic to a small bowl and mash with a fork. Add thyme and mustard and mix well, making a paste. Set aside for 15 minutes or so to let flavors mature.
Season steaks with kosher salt and pepper and baste with the olive oil/butter on both sides. Cook steaks on a hot grill for 4 -5 minutes each side. Baste with the oil/butter periodically. When steaks are almost done, cover each generously with the mustard/garlic paste. Top with a generous amount of parmesan cheese. Continue grilling until cheese and mustard form a crust. Let steaks rest five minutes before eating.