Cut a thin slice from the top of the loaf. Scoop out most of the bread. Tear to make 1 1/2 cups soft crumbs (top slice and remaining bread can be used as bread crumbs in other recipes). Brown onion and mushrooms in 1 1/2 tbs. of the butter. Beat egg with catsup. Mix in bread crumbs, 1/2 cup of the cheese, wine and seasonings. Lightly mix in ground beef and onion mixture. Spoon meat mixture into hollowed-out bread. Rub crust with remaining 1/2 tbs. butter. Wrap in foil. Bake at 375 for 1 hour to 1 1/4 hours. Fold back foil and sprinkle with remaining 1/2 cup cheese. Return loaf to oven. Bake until cheese melts, about 3 minutes. Cut into 1 inch slices.