To prepare the steaks: Rub steaks with garlic clove, salt and cracked pepper. Marinate in Worcestershire sauce for 1 hour, minimum.
To prepare the ragout: Grill mushrooms whole, then coarsely chop into 3/4-inch cubes. Pour olive oil in pan, add mushrooms and shallots, and saute until soft. Add tomatoes, heavy cream, and stock. Simmer and reduce for about 10 minutes. Add herbs and seasonings and remove from heat. Keep warm if using immediately.
To cook steaks and prepare cognac butter: Sear steaks in a heavy skillet on high heat to desired temperature, remove from heat. Add cognac and flame off, then whisk in the butter.
Place mushroom ragout on plate. Cut steaks across the grain into 1/2-inch slices. Fan steaks on top of ragout and drizzle with cognac butter. Garnish as desired. Serve immediately.