HEAT oven to 350°F. Place 24 paper baking cups in muffin pans.
BEAT cake mix, oil, water and eggs in large bowl with electric mixer on medium speed 2 minutes. Remove 1/2 cup batter and stir in hot fudge topping until evenly blended. Put 2 tablespoons yellow batter in the bottom of each baking cup. Place 1 heaping teaspoon fudge batter in middle of each cupcake. Top with 1 tablespoon yellow batter, smoothing to cover fudge.
BAKE 20 minutes or until toothpick inserted in center comes out clean. Cool completely on cooling rack. Frost with chocolate fudge frosting