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ruby chocolate cake recipe by sugar and sparrow

Ruby Chocolate Cake Recipe

Layers of decadent chocolate cake, filled and frosted with a silky smooth ruby chocolate buttercream to create beautiful notes of raspberry that perfectly balance the chocolate flavor. Topped with ruby chocolate ganache and featuring an all-natural mauve color palette!

Prep Time 25 minutes
Cook Time 45 minutes

Ingredients

One-Bowl Chocolate Cake

  • 2 Cups (265g) all purpose flour
  • 1 2/3 Cups (340g) white granulated sugar
  • 2/3 Cup (60g) unsweetened natural cocoa powder (not Dutch Process)
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1/2 tsp kosher salt
  • 1/2 Cup (120ml) vegetable oil
  • 2 eggs, room temperature
  • 1 1/2 tsp pure vanilla extract
  • 1 Cup (240ml) full-fat buttermilk*, room temperature DIY recipe in the notes
  • 1 Cup (240ml) hot water

Ruby Chocolate Buttercream

  • 9 oz (255g) ruby cacao, chopped into small bits
  • 1 1/2 Cup (339g) unsalted butter, room temperature
  • 2 1/4 Cup (270g) powdered sugar
  • 1 1/2 tsp pure vanilla extract
  • 1/3 Cup (80ml) heavy whipping cream, room temperature
  • 1/2 tsp kosher salt

Ruby Chocolate Ganache

  • 6 oz (170g) ruby cacao, chopped into small bits
  • 1/2 Cup (120ml) heavy whipping cream
  • 1-2 drops Americolor Fuschia or pink food color gel optional

Instructions

Make The Chocolate Cake

  1. Preheat the oven to 350ºF and prepare three 6-inch cake pans or two 8-inch cake pans by spraying the sides with cooking spray and fitting the bottoms with a wax paper or parchment cake circle.

  2. Place all of the dry ingredients into the bowl of a stand mixer and stir on low for 30 seconds to fully combine them. Add the vegetable oil, eggs, vanilla, and buttermilk and mix on low until just combined. With the mixer still on low, add the hot (just boiled) water in a slow stream, then turn the mixer to medium and beat until smooth, about 2 minutes. The batter will be very thin.

  3. Pour into prepared cake pans no more than 2/3 full and bake for 40-45 minutes, until a wooden toothpick inserted comes out clean. Cool completely before frosting.

Make The Ruby Chocolate Buttercream

  1. Add the ruby chocolate into a glass bowl and microwave for 30 seconds. Stir, then microwave for another 30 seconds. Stir until all the ruby chocolate is melted and there are no lumps. Alternatively, you can melt the ruby chocolate using a double boiler. Set aside to cool slightly.

  2. In the bowl of a stand mixer fitted with a paddle attachment, beat the butter on high until light and fluffy, about 4 minutes. Turn the mixer to low, add the powdered sugar, and mix until well combined. Scrape down the bowl and paddle, give the melted ruby chocolate a few stirs and make sure it’s not hot enough to melt the butter (if it is still too hot, wait a few minutes before adding!), then add it in. Turn the mixer to medium speed and beat for 2 minutes, until the mixture is smooth. Add the vanilla, heavy whipping cream, and salt and beat for another minute on medium.

Make The Ruby Chocolate Ganache

  1. Place the chopped ruby cacao into a glass or metal bowl and set aside. In a saucepan over medium-high heat, warm heavy whipping cream until it just starts to boil. I always look for small bubbles forming around the edge and a soft boil starting in the middle. When you see that it’s just starting to boil, pour it over the ruby cacao bits and let sit for about 20 seconds.

  2. Whisk it together until it’s uniform in consistency and there are no bits of chocolate left on your whisk. Add a drop or two of Americolor Fuschia or pink food color gel of your choice if you want (the natural ganache color turns out more beige-toned for some reason).

  3. Cool ganache at room temperature for about 30 minutes, or until the ganache itself is close to room temperature (a little warmer may be fine depending on how thin you like your drips).

Assembly

  1. When the chocolate cake layers have cooled completely, torte them before filling and frosting with ruby chocolate buttercream. Chill the frosted cake in the refrigerator for at least 20 minutes before dripping with the room temperature ruby chocolate ganache. It’s always best to do a test drip on the cake before dripping the whole thing - that way you can see whether you need to cool the ganache more or gently warm it in the microwave before committing to dripping the rest of the cake.

  2. After dripping the cake with ganache, place it in the refrigerator for at least five minutes to let it set. To create the design pictured, place a few tempered ruby chocolate disks on top of the cake (I splatter painted mine with Americolor Bright White). Use the remaining ruby chocolate buttercream to pipe rosettes with Wilton tip 1M and stars with Wilton tip 4B wherever you desire!

Recipe Notes

DIY Buttermilk recipe: add 1 Tbsp of white vinegar to a jar and top it with 1 Cup of whole milk. Stir and let sit for 15 minutes before using in the recipe. 

Make ahead tips: 

  1. The chocolate cake recipe can be made ahead and stored at room temperature, covered tightly in plastic wrap, for up to two days. Alternatively, you can cover with plastic wrap and store in the freezer for up to two months before thawing to room temperature. 
  2. The ruby chocolate buttercream can be made ahead and stored in an airtight container at room temperature for one day. Alternatively, you can store it in an airtight container in the refrigerator for up to two weeks. When you’re ready to use it, bring it back to room temperature and re-whip with your stand mixer to bring it back to piping/frosting consistency.
  3. The ruby chocolate ganache can be made ahead and stored in the refrigerator in an airtight container for up to two weeks. When you’re ready to use it as a drip, microwave it in 10 second increments, stirring after every interval until your ganache is room temperature and uniform in consistency.