Chocolate Mayonnaise Cake with Penuche Frosting

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This recipe bakes in a 9″ square pan making it a great choice for a smaller family or one or two people. You can use any frosting you wish; chocolate, vanilla buttercream, or peanut butter are good choices, but my favorite pairing with this cake is Penuche frosting. Penuche is a sort of fudge with a caramel flavor made with brown sugar, butter and milk – this frosting is all that in spreadable form.

There no eggs or oil listed for this recipe because the mayonnaise provides them. NOTE: Use only full fat mayonnaise in this recipe,  not low fat or fat free to obtain the correct results.

Chocolate Mayonnaise Cake with Penuche Frosting

Recipe by A Coalcracker in the KitchenCourse: DessertCuisine: Coal Region, Pa. DutchDifficulty: Intermediate


  • 2 cups Flour

  • 1 cup Sugar

  • 1 teaspoon Baking Soda

  • 1 teaspoon Vinegar

  • 1 cup Mayonnaise (Use only full fat mayonnaise, not low fat or fat free)

  • 1 teaspoon Vanilla

  • 1 cup Cold Water

  • 1/4 cup Cocoa powder

  • frosting

  • 1/2 cup butter (1 stick)

  • 1 cup dark brown sugar

  • 1/4 cup half-and-half

  • 1 pinch salt

  • 1 teaspoon vanilla extract

  • 2 cups confectioners’ sugar (or as need to make desired consistency)


  • In a large bowl, combine the water, mayonnaise, vinegar and vanilla until well blended. Set aside.
  • Pour into greased 9-inch square or 11 x 7-inch baking pan.
  • Bake at 350° for 30-35 minutes or until a toothpick inserted in the center comes out clean.
  • Cool completely and frost.
  • Penuche Frosting
  • Melt the butter in a saucepan over medium heat. Stir in brown sugar and bring the mixture to a boil. Reduce the heat and continue to simmer for 2 minutes, stirring constantly.
  • Stir in half-and-half and salt and return to a boil, continuing to stir.
  • Remove the caramel from the heat and allow to cool to lukewarm, then add vanilla.
  • Gradually beat in confectioners’ sugar with an electric mixer until smooth, being careful not to over-beat. If the frosting becomes too thick, hot water can be added to thin it out.
  • Spread over cooled cake.
  • Allow the frosting to set before serving, about 15 minutes.


  • Use only full fat mayonnaise in this recipe to obtain the correct results., not low fat or fat free.