Sauté mushrooms and garlic in 2 tablespoons butter in skillet over medium heat until tender. Remove from pan. Melt remaining 2 tablespoons butter in skillet; stir in flour to make a paste. Combine broth and water; slowly add to paste; simmer for 2 minutes; add salt, pepper and thyme. Add mushroom and half-n-half, stirring until combined; add in mushroom garlic mixture and heat until hot; do not boil. Preheat oven on broil. Sprinkle steaks with lemon pepper, place on broiler pan and broil 3 to 5 inches from source of heat for 7 to 10 minutes per side for medium-rare (depending on thickness of meat) or to desired degree of doneness. For outdoor charcoal grilling, place steaks over moderately hot coals and grill for 5 to 8 minutes per side for medium-rare, or to desired degree of doneness. Allow to rest 5 to 10 minutes. Serve steak with warm mushroom cream sauce.