Lightly grease the inside of 4 (8-oz.) mugs. Prepare brownie mix according to directions on package and divide batter evenly between 4 mugs. Microwave all 4 mugs on high 4 to 4 1/2 minutes or until toothpick comes out clean when inserted into batter. Let cool. Place heaping scoop of ice cream on top of each mug. Heat hot-fudge sauce according to directions on label and pour over ice cream until ice cream is completely covered. Stand two mint wafers up and place them side by side on top of head to form ears. Spray two small circles of whipped cream on each to make eyes and make one larger oval-shaped mound going across underneath for snout. Place a chocolate-covered peanut in the center of each eye and cherry in center of snout for mouse. Sundae cups can be served immediately or placed in freezer to enjoy later.