I just made this tonight- that's how I found this post... but then I found the magazine... here you go.

Chunky Monkey Cake

3 Ripe bananas (1 to 1 1/4 lbs)
1 pkg yellow cake mix (i.e Duncan Hines)
3 eggs
1/3 cup canola oil
2/3 cup chopped walnuts
1/2 cup semisweet chocolate chips
3 cans (16 oz each) milk chocolate frosting
Ben & Jerry's Chunky Monkey Ice Cream (optional)

Preheat oven to 350 F. Coat 2 9-inch round cake pans with cooking spray. Mash 2 of the bananas.

At low speed beat cake mix, 1 1/3 cup water, eggs, and oil until combined; beat 1 minute. Add mashed bananas. Beat until smooth, 3 minutes

Chop remaining banana into 1/2-inch pieces. Using rubber spatula, fold banana, chopped walnuts, and chocolate chips into batter. Evenly divide batter between pans.

Bake about 30 minutes or until toothpick in center comes out clean. Cool in pans on racks for 10 minutes. Carefully remove cakes from pans; cool completely on racks.

Fill large pastry bag with star tip. Place pastry bag in tall glass, folding edges over glass. Fill Bag with 3/4 cup frosting; reserve for rosettes.

Place one cooled cake layer on serving platter; spread with 1 cup milk chocolate frosting. Top with remaining cake layer; spread top and side with remaining frosting.
Twist end of pastry bag to close. Pipe rosettes or mound frosting onto top of cake.

Serve with ice cream, if desired.

I made this, and preferred to make in 8-inch pans rather than 9-inch ones. The Bananas make it VERY moist and yummy... I also didn't need 3 cans of frosting... I only used one and a half, but that's cause I only like SOME frosting...
HTH! Meta :)