1Heat oven to 350°F (325°F for dark or nonstick pans). Make, bake and cool cake as directed on box for two 8- or 9-inch rounds--except add 1 tablespoon espresso and the cinnamon with the eggs, and stir in the chocolate just before pouring into pans.
2To make glaze, spoon frosting into small microwavable bowl. Microwave uncovered on High 15 to 30 seconds or until slightly melted. Stir in 2 teaspoons coffee until blended.
3Place 1 cake layer, rounded side down, on serving plate. Carefully spread almost half the glaze to edge of layer, allowing some to drip down side. Top with second layer, rounded side up. Carefully spread remaining glaze to edge of top layer, allowing some to drip down side. Store loosely covered.