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Peanut Butter & Chocolate Marble Cake (Vegan)

Peanut Butter & Chocolate Marble Cake – The perfect mix of two irresistible cake flavors! Rich chocolate cake marbled with a light and fluffy peanut butter cake, topped with decadent chocolate frosting.

Peanut Butter & Chocolate Marble Cake

Can I be honest? I had pretty much the best birthday this year.

I’ve literally been celebrating my birthday for the past week. I’m doing something cool every day and taking down time to watch movies I’ve always wanted to watch. Plus I cleaned and organized our entire house, because yes I’m actually 65 and organizing is genuinely fun to me. There’s a feeling you get when you buy new baskets from Target that I can’t quite explain, but it’s a feeling I live for.

Peanut Butter & Chocolate Marble Cake

I got the most thoughtful presents from my boyfriend and family (mostly stuff for streaming), and of course I got to eat. A lot. Mostly cake. And since it was my birthday, I took my two favorite cakes of all time, smashed them together with my favorite frosting, and the end result is ethereal.

I’m a peanut butter girl through and through, and I never seem to get tired of it. I took my favorite peanut butter cake recipe, marbled it together with rich chocolate cake, and topped the whole thing with a chocolate frosting that I could eat by the spoonful.

Peanut Butter & Chocolate Marble Cake

How to Make Peanut Butter & Chocolate Marble Cake:

First, make the two cake batters. Then in an 8″x8″ pan, alternate big scoops of the batters. I covered almost the entire bottom of the pan with peanut butter batter, leaving just a few empty spots, then poured over the chocolate batter and topped with the remaining peanut butter. The chocolate batter is much thinner, so it’ll pour easily into all the nooks and crannies. Then if you want to, use a knife to gently swirl the two batters together. Bake until the peanut butter cake is golden, let it cool, then top it with the chocolate frosting.

Peanut Butter & Chocolate Marble Cake

I doubled the entire recipe and baked it in a 9″x13″ pan because I wanted to feed a small army, but if you want to bake a normal amount of cake then follow the recipe as is.

I also added freeze-dried strawberries on top and… there are no words.

Peanut Butter & Chocolate Marble Cake

Peanut Butter & Chocolate Marble Cake

Brit Wolfe
Prep Time 15 mins
Cook Time 30 mins
Total Time 45 mins
Course Cake


Peanut Butter Cake

  • 6 Tbsp. creamy peanut butter
  • 3 Tbsp. vegan butter, such as Earth Balance
  • 1/4 cup granulated sugar
  • 1/4 cup brown sugar
  • 1 1/2 Tbsp. ground flaxseed
  • 1 cup + 2 Tbsp. all-purpose flour
  • 1 tsp. baking powder
  • 1/2 tsp. baking soda
  • 1/4 tsp. salt
  • 1/2 cup nondairy buttermilk

Chocolate Cake

  • 3/4 cup all-purpose flour
  • 2 Tbsp. cocoa powder unsweetened
  • 1/2 cup granulated sugar
  • 1/4 tsp. salt
  • 1/2 tsp. baking soda
  • 3 Tbsp. vegetable oil
  • 1 1/2 tsp. white vinegar
  • 1/2 tsp. vanilla extract
  • 1/2 cup freshly brewed coffee cold

Chocolate Frosting

  • 1/2 cup vegan butter, such as Earth Balance
  • 1/4 tsp. salt
  • 1/2 tsp. vanilla extract
  • 1 Tbsp. + 1 tsp. cocoa powder unsweetened
  • 6 ounces semisweet chocolate chips
  • 1 1/2 cups powdered sugar
  • 1 Tbsp. nondairy milk, such as Silk optional


To make the peanut butter cake:

  • Preheat the oven to 350ºF.
  • In a small bowl, mix the ground flaxseed with 4 1/2 Tbsp of water. Mix well, then set aside to let thicken slightly, about 5-7 minutes.
  • In the bowl of a stand mixer, cream together the butter, peanut butter, and sugars until light and fluffy, about 5 minutes. Add the flaxseed and mix for another 3 minutes until fully incorporated.
  • Sift together the dry ingredients (flour, baking powder, baking soda, and salt). Alternately add the dry ingredients and the buttermilk (meaning add 1/3 of the dry, 1/2 of the wet, 1/3 of the dry, remaining wet, remaining dry).
  • Set aside while you make the chocolate cake batter.

To make the chocolate cake:

  • In a large bowl, sift together the dry ingredients (flour, cocoa powder, salt, and baking soda). Add the sugar and mix well.
  • In a measuring cup, mix together all the wet ingredients (oil, vinegar, vanilla, and coffee). Add the wet ingredients to the bowl, then gently stir until no lumps remain.

To assemble:

  • Generously spray an 8″x8″ baking pan with baking spray. Alternate adding the two batters to the baking pan.
  • Once they have both been added, use a knife to gently swirl the two batters together. Be sure to swirl gently, or the two batters will blend together and you won’t get the marble effect!
  • Bake the cake for 30-40 minutes, or until a toothpick inserted in the center of the cake comes out clean.

To make the frosting:

  • In the bowl of a stand mixer, cream the butter until smooth. Add the salt and vanilla and continue creaming until light and fluffy, about 5 minutes.
  • In a microwave-safe bowl, add the chocolate chips. Microwave the chocolate in 30-second intervals until completely melted. Let cool slightly.
  • With the mixer on medium, add the melted chocolate. The easiest way to do this (without making a mess!) is to pour the chocolate straight down the side of the bowl into the mixer.
  • Once fully incorporated, sift together the powdered sugar and cocoa powder and add it to the bowl. Start the mixer on low until the powdered sugar is fully incorporated, then turn the mixer to medium-high to whip some air into the frosting.*
  • If your frosting is a little too thick, add the nondairy milk and continue mixing until light in color and super fluffy.
  • Spread the frosting over the cooled cake and decorate with sprinkles or freeze-dried fruit. Enjoy!


*Sometimes the frosting can look broken at this point. If it looks gritty or broken, just continue whipping it on a high speed until it all comes together. If it continues to look broken, place the bowl in the fridge for 10-15 minutes until the frosting is cool, then whip it on a high speed.
To make homemade buttermilk, add 1/2 tsp. of lemon juice to a 1/2 cup measuring cup, then fill the rest with nondairy milk. Mix well, then let sit for 5 minutes until curdled.
Frosting recipe by Joy the Baker
Peanut Butter & Chocolate Marble Cake

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Peanut Butter & Chocolate Marble Cake

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