Heat oven to 350°F (325°F for dark or nonstick pan). In small bowl or 2-cup measuring cup, mix topping and 1 tablespoon of the dry cake mix. In large bowl, stir together remaining dry cake mix, the butter and egg, using fork, until crumbly. Reserve 1 cup crumb mixture. Using a piece of plastic wrap on crumb mixture, press remaining mixture in bottom and 1/2 inch up sides of ungreased 9-inch square pan; remove wrap.