Crew’s Mess: Chocolate Marbled Banana Cake

Apr 25, 2020 by Capt. John Wampler

Crew’s Mess: by Capt. John Wampler

Capt. John Wampler ( has worked on yachts for more than 30 years. His recipes are casual enough for anyone to prepare, especially crew cooking for each other.

Chocolate and bananas go together like peas and carrots. Growing up in the foothills of Southern California, chocolate-covered frozen bananas were a treat on the weekends at the beach. Closer to home, a banana spread with Nutella made for a high-energy treat. 

This delicious combination is the inspiration for this month’s recipe. Easy to prepare with items already in your pantry, this is just the thing to bring to a springtime pot-luck dinner or barbecue.  

Chocolate Marbled Banana Cake


  • 2 1/2 cups (10 3/4 ounces) all-purpose flour
  • 1 teaspoon baking soda
  • 1 1/4 cup (9 1/2 ounces) brown sugar, firmly packed
  • 1/4 cup (2 ounces, or 56 grams) salted butter, softened
  • 1/2 cup (4 fluid ounces) full-fat sour cream, room temperature
  • 1 1/2 cup mashed banana (2 or 3 large)
  • 1 large egg, room temperature
  • 1 teaspoon pure vanilla extract
  • 3/4 cup (4 1/2 ounces) semisweet chocolate chips, melted and cooled


  • Preheat oven to 350F.
  • Spray an 8-by-8-inch or 9-by-9-inch baking pan with nonstick baking spray.
  • In medium bowl, combine flour and baking soda, then mix with a wire whisk. Set aside.
  • In a large bowl, blend the brown sugar and butter with a hand mixer or stand mixer, then scrape the sides of bowl.
  • Add the banana and beat on medium until the mixture is smooth. 
  • Add the sour cream, egg and vanilla, then beat again on medium until smooth. 
  • Add the flour mixture all at once and blend on low until just combined, don’t over mix. 
  • Pour the melted chocolate in a stream over the top of the mixture, then  fold it in by hand with just a few turns until the mixture is marbled. 
  • Pour the batter into the prepared pan. 
  • Bake 45 minutes, or until a toothpick inserted in the center comes out clean. 
  • Remove the pan from the oven and set it on a cooling rack for 15 minutes to allow the cake to firm up a bit, then turn the cake out of the pan and place it right side up on the cooling rack. Cool to room temperature.


  • 3/4 cup (6 fluid ounces) heavy cream
  • 1 cup (6 ounces) semisweet chocolate chips


  • Microwave the heavy cream in a small microwave-safe bowl for 1 to 2 minutes until it’s steaming, then add the chocolate chips and set aside for 10 to 15 minutes.
  • Stir ganache until it is smooth, then refrigerate uncovered 30-40 minutes, stirring once or twice.
  • When it has reached about 70F, the ganache should mound and be spreadable without flowing.
  • Frost the cake top and sides with the ganache.

Optional decoration:  Melt a 2-ounce white chocolate baking bar on medium/low heat, stirring every 30 seconds until it is completely melted. Pour into a disposable icing bag or a quart-size plastic bag with a corner cut off. Drizzle decoratively over the top of the frosted cake. 

Yield: 9-12 pieces.