01 -
Preheat oven to 350°F. Grease and line the bottoms of two 8- or 9-inch round cake pans with parchment paper.
02 -
In a large bowl, combine cake mix, room-temperature coffee, vegetable oil, and eggs. Beat on medium speed with an electric mixer for 2 minutes until smooth. If using, add 1 teaspoon black gel food color and mix well.
03 -
Divide batter evenly between prepared pans. Bake for 24 to 28 minutes or until a toothpick inserted into the center comes out clean. Allow cakes to cool in pans for 10 minutes, then invert onto wire racks to cool completely.
04 -
In a medium bowl, combine chocolate frosting with 2 teaspoons black gel food color. Beat until the frosting is uniformly colored and smooth.
05 -
Place one cake layer on a serving plate. Spread approximately one-quarter of the frosting evenly over the top. Place second layer on top, then cover the entire cake with the remaining frosting.
06 -
Microwave 1/3 cup mini marshmallows in a microwave-safe bowl for 10 to 15 seconds until puffed. Wearing clean disposable gloves, stretch the warmed marshmallows between your hands to form thin strands. Drape and wrap these strands over the cake surface to resemble a spiderweb. Repeat with remaining marshmallows until the cake is covered. Garnish with plastic spiders if desired.