Rhubarb Cake with Creamy Rhubarb Jam and Buttercream
Mini vanilla cakes with rhubarb pieces, layered with creamy rhubarb jam and topped with a pink American buttercream frosting.
Servings 24 servings
Calories 354kcal
Ingredients
Rhubarb Cake
- 2 ¾ Cups Flour
- ¼ Cups Cornstarch
- 1 ½ Cups Granulated Sugar
- 1 tsp Baking Powder
- ½ tsp Baking Soda
- ½ tsp Salt
- 1 cup Unsalted Butter cubed and room temperature
- 1 Tbsp Vanilla extract
- 1 Cup Milk room temperature, divided
- 3 Eggs room temperature
- ½ Cup Greek Yogurt room temperature
- 1 ½ Cups Rhubarb trimmed and roughly chopped
Creamy Rhubarb Jam
- 2 Tbsp Butter
- 1 ½ Cup Rhubarb trimmed and roughly chopped
- ½ Cup Sugar
- ¼ Cup Heavy Cream
- pinch Sea Salt
American Buttercream
- 1 Cup Unsalted Butter room temperature
- 3 Cups Confectioner's Sugar
- 2-4 Tbsp Milk
Instructions
Bake the Rhubarb Cake
- Preheat the oven to 350°F with a rack in the center. Line a 9x13 baking pan with parchment paper and grease the paper.
- In the bowl of a stand mixer fitted with the paddle attachment, sift together the flour, cornstarch, sugar, baking powder, baking soda, and salt. Mix on low for a few short bursts to combine.
- Add in the butter, vanilla, and half the milk and mix together on medium low until the butter is incorporated into the flour mixture and everything is moist, about 1 minute. The texture should be similar to a pie crust dough.
- Then add in the eggs, yogurt, and remaining milk. Mix just until everything is combined, stopping every few seconds to scrape down the sides of the bowl with a silicone spatula. Total mixing time should be about 1 minute.
- Fold in the rhubarb pieces with a silicone spatula and then transfer the batter to the prepared baking pan.
- Bake the cake for 35-45 minutes, checking a bit early to see if it is done. A toothpick may come out clean before the center is fully cooked. Double check by gently pressing on the cake. If it bounces back, it's done. If not, continue baking.
- Allow the baked cake to cool completely in the pan on a wire rack.
Make the Creamy Rhubarb Jam Filling
- While the cake is cooling, melt the butter in a medium saucepan over medium heat. Then add in the rhubarb and sugar. Cook, stirring occasionally as the rhubarb begins to softened and form into a thick jam-like texture, about 8-10 minutes.
- Turn off the heat and stir in the heavy cream. Transfer the filling to a jar. Cover loosely and allow to cool to room temperature. Then seal and store in the fridge for 1-2 days if needed.
- Carefully use the parchment paper (and a friend if needed) to lift the completely cooled cake out of the pan and onto a work surface. Using 4-inch diameter round cookie or biscuit cutters, cut out 6 circles of cake. Place the scraps in a bowl and set aside.
- Using a cake leveler or serrated knife, cut each round cake into two vertical layers. Spread 1-2 tablespoons of the filling on the bottom half of each cake, and top with the other half. Chill the cakes in the fridge for an hour.
- Break down the cake scraps into crumbles. Cover and let sit aside at room temperature while the cakes chill and you prepare the frosting.
Make the Buttercream and Decorate
- In the bowl of a stand mixer fitted with the paddle attachment, add the butter and whip on medium speed until visibly lightened in color and fluffy, about 1-2 minutes.
- Add in the sugar 1 cup at a time and completely incorporate each cup before adding the next. Stop to scrape down the sides of the bowl in between.
- Add the milk as needed to achieve your desired texture. Piping frosting will require it slightly less stiff than if you are spreading. Add any food coloring you would like and mix to incorporate. I used 1 drop of red gel and a toothpick dipped in blue gel for this bright pink color. Transfer the icing to a piping bag with no tip if desired.
- Remove the cakes from the fridge and place one on a turntable, cake stand, or other flat surface that you can work around or spin. Pipe frosting around the sides and on top of the cake, and then spread using a mini offset spatula or butter knife. Scrape of any excess and repeat for the rest of the cakes.
- Top each cake with the leftover cake crumbles. Cut in quarters to serve immediately, or store for later.
Notes
- Make ahead tips:
- Store the unfrosted cake covered at room temperature for 1-2 days. The unfrosted cake can be tightly wrapped and frozen for 2-3 months. Thaw in the fridge overnight before decorating.
- The creamy rhubarb jam can be sealed and stored in the fridge for 1-2 days, once cooled to room temperature.
- Make buttercream frosting up to 2-3 days in advance and store in the fridge. Let it thaw to room temperature before using. You may need to remix it with another splash of milk if too thick.
- Decorated cakes can be stored in the fridge for 2-3 days or wrapped tightly and frozen for 2-3 months. Thaw in the fridge overnight before eating. The finished cake can be served directly from the fridge or after warming to room temperature.
- If you end up with leftover cake scraps, creamy rhubarb jam, and/or buttercream, combine them all together in a bowl and dip in melted white chocolate to make cake pops!