Who needs to choose between chocolate and vanilla on their birthday – why not have both! This marble birthday sheet cake is easy to assemble and will please anyone that you are looking to surprise with a delicious and fun cake on their special day. You really can have it all on your birthday!
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Things were a little bit different this year for my birthday with the whole quarantine situation. I’m an April baby! Any other April birthdays out there? Aren’t we lucky to have a quarantine birthday this year?
But in all honesty, it was one of the best birthdays I’ve had! Because things have been less busy, I was able to chat with my parents and my mother-in-law which NEVER happens. Life just gets so chaotic sometimes. It was wonderful to relax and just enjoy the day. And, I also was able to take my sweet time making this delicious and easy marble birthday sheet cake!
I really had a hard time deciding whether I wanted vanilla or chocolate cake this year so I thought I would do both!
As for the frosting, that was an easy choice. I topped it with a thick and creamy chocolate buttercream frosting. It’s the absolute best. Do you prefer vanilla or chocolate frosting? Or no frosting? If you’re a no frosting kind of person, we probs can’t be friends… juuuuust kidding! I’m definitely all about the chocolate frosting. Give me all of the chocolate on my birthday. Or on any day really.
Making Easy Marble Birthday Sheet Cake
This marble birthday sheet cake is ridiculously easy to assemble because it only requires that you make one batter! You will start with a yellow cake batter and then add melty dark chocolate to a small portion to get your chocolate part.
Adding melted chocolate vs. cocoa powder to the chocolate portion of the cake give it a much more fudgy and rich texture. The swirls of vanilla batter and the dark, fudgy chocolate batter really make this cake extra yummy!
The recipe for this marble sheet cake will make one 9×13 inch cake but you can certainly turn this into a layer cake instead! You will simply divide the batter up between two 9-inch round cake pans and cook for 22-25 minutes or so (less for high altitude), depending on your oven. I like the sheet cake because it takes less time to decorate and looks just as adorable! Plus, it is easy to transport right in the pan.
High Altitude Adjustments
For those of you living at high altitude (3,000 feet elevation and above), I have included a few adjustments that kept my cake from falling flat! For reference, I live at around 5,800 feet above sea level, and you may need to slightly adjust based on higher/lower elevation:
- Flour – increase by 2 tbsp. for extra structure, especially because this recipe calls for cake flour. Cake flour has less protein and structure than normal, all-purpose flour and so it’s really important to increase the amount to give the cake more lift.
- Baking Powder – decrease by 1 tsp. so that the batter does not rise as quickly when cooking. This will prevent a sunken cake!
- Eggs – use 1 egg white in addition to the 4 egg yolks for extra moisture since things dry out at higher elevations faster.
- Granulated Sugar – decrease by 1 tbsp. so that the concentration of sugar is less. More sugar weakens the structure of the cake.
- Oven Temperature – increase to 360° F. The higher temperature helps your cake set faster which decreases the risk for sinking!
- Cook Time – I cooked mine for 30 minutes. Watch your cake closely because you will need to cook for less time due to the higher temperature!
For more tips on high altitude baking, you can check out this article! I always post the recipe as is for sea level, and then these notes which will also be in the “Notes” section of the recipe.
Apparently I Really Like Cake
Alright, I also just realized that this is the THIRD cake recipe in a row now that I’ve posted. I promise I will switch things up but of course, I had to have a cake for my birthday!
I hope that you enjoy this easy marble birthday sheet cake! It’s a great recipe to save for birthdays or really any other special occasion. Pin it for later and tag me if you end up making this for someone’s special day! It truly warms my heart to see you baking my recipes!
And Happy Birthday to all of the April Babies!
If you are looking for another fun birthday dessert, try these Funfetti Blondies, this Vanilla Bean Layer Cake with Strawberry Frosting, or my Classic Yellow Layered Birthday Cake! These Double Dark Chocolate Cupcakes are always a hit as well.
Marble Birthday Sheet Cake
Ingredients
For the Marble Birthday Sheet Cake
- 2 cups cake flour
- 2 tsp baking powder
- 1/2 tsp salt
- 1 cup unsalted butter, 2 sticks (room temperature)
- 3/4 cup granulated sugar
- 1/2 cup light brown sugar
- 2 large eggs (room temperature)
- 4 egg yolks (room temperature)
- 1 tbsp vanilla extract
- 2/3 cup buttermilk (room temperature)
- 4 oz chopped dark chocolate (I use Lindt 70% Dark Chocolate Bars)
For the Dark Chocolate Buttercream
- 1 cup chopped dark chocolate (I use Lindt 70% Dark Chocolate Bars)
- 1½ cups unsalted butter (room temperature)
- 1 tsp vanilla extract
- ¼ tsp salt
- 2¼ cups powdered sugar
Instructions
For the Marble Birthday Sheet Cake
- For High Altitude Instructions, see Notes.
- Preheat oven to 350°F. Line a 9×13 inch baking pan with parchment paper, or grease the pan if you don't plan to remove the cake from the pan. Set aside.
- Sift together the cake flour, baking powder and salt in a large bowl. Set aside.
- In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the butter on high speed until light and fluffy (about 1 minute).
- Add the granulated and brown sugars to the butter and beat on high speed until pale and fluffy (about 3-4 minutes).
- With the mixer running on low speed, add the eggs one at a time until well combined. Next, add the yolks one at a time until fully incorporated. Scrape down the bowl if needed and add the vanilla extract. Beat on medium-high speed until combined.
- With the mixer running on low, slowly add in the dry ingredients in 3 portions, alternating with 3 portions of the buttermilk. Mix until just incorporated but do not over mix.
- Remove one cup of the yellow cake batter and pour into a medium bowl. In a small pan on the stove over low heat, or in the microwave in 20 second intervals, melt the chocolate. Let cool slightly and fold into the reserved yellow cake batter.
- Pour half of the yellow cake batter into the 9×13 inch cake pan. Carefully spread until evened out in the pan if needed.
- Next, spoon equal dollops of the chocolate cake batter into the pan. Finish by pouring your remaining yellow cake batter over the top. Don't worry, it doesn't need to be perfect because you are going to swirl!
- Take a knife and gently swirl the two batters together.
- Bake for 30- 35 minutes, or until a toothpick inserted into the center comes out clean. Just be sure to carefully watch so that it does not overbake. It really depends on your oven!
- Remove from oven and cool on a wire rack in the pan. Frost the cooled cake with Dark Chocolate Buttercream or any frosting you would like. Add sprinkles too!
For the Dark Chocolate Buttercream
- Melt the chopped chocolate in a small saucepan on the stove over low heat or in a bowl in the microwave in 20 second intervals. Once melted, set aside to cool slightly.
- In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, cream the butter on medium-high speed until very light and fluffy (about 3 minutes).
- Add the vanilla and salt and beat on medium speed until just combined.
- Reduce the mixer to low speed and gradually add the powdered sugar. Once combined, increase speed to medium-high and beat until smooth and fluffy (about 3 minutes).
- Scrape down the sides of the bowl and add the melted chocolate. Beat on medium speed until well combined.
- Frost cooled cake and enjoy!
Notes
- Flour – increase by 2 tbsp.
- Baking Powder – decrease by 1 tsp.
- Eggs – use 1 egg white in addition to the 4 egg yolks called for
- Granulated Sugar – decrease by 1 tbsp.
- Oven Temperature – increase to 360° F.
- Cook Time – I cooked mine for 30 minutes. Watch your cake closely because you will need to cook for less time due to the higher temperature!
