Marble Birthday Sheet Cake
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!
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 9x13 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 9x13 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
For a Layer Cake - Divide batter between two greased 9-inch round cake pans and bake for 20-25 minutes, depending on your oven (less time for high altitude).
You can always frost this with vanilla buttercream or other frosting. Get creative with it!
This cake can be stored in an airtight container in the refrigerator for up to 3 days. To serve, bring to room temperature and slice.
High Altitude Instructions
- 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!