Go Back
Sumikko Gurashi Rainbow Cake

Sumikko Gurashi Rainbow Cake

Rainbow layer vanilla cake with Sumikko Gurashi cookie decorations
Print Recipe Pin Recipe
Course Dessert

Ingredients
  

Stamped Cookies

  • 2 2/3 cups (300 g) all-purpose flour
  • 2 tbsp cornstarch
  • 1 cup (200 g) sugar
  • 1/2 tsp salt
  • 8 oz (113 g) unsalted butter room temperature, cut into 1-in pieces
  • 1 large egg
  • 1 tbsp vanilla extract
  • 1 tsp almond extract

Vanilla Layer Cake

  • 2 3/4 cups (380 g) cake flour
  • 1 3/4 cups (380 g) sugar
  • 1 tbsp + 1 tsp (18 g) baking powder
  • 1 1/8 tsp salt
  • 7 oz (200 g) unsalted butter room temperature
  • 5 large egg whites room temperature
  • 1 large egg room temperature
  • 1 1/2 cups (366 g) whole milk
  • 2 tsp vanilla extract

Swiss Meringue Buttercream

  • 1 1/4 cups sugar
  • 5 large egg whites
  • 15 oz (425 g) unsalted butter room temperature, cut into 1-in pieces
  • 1 1/2 tsp vanilla extract
  • 1 1/2 tsp almond extract

Instructions
 

For the cookies

  • Combine the flour, cornstarch, sugar, and salt in the bowl of a stand mixer fitted with the paddle attachment. Mix until combined.
  • Add in the butter and beat until incorporated and the mixture looks like rough crumbs. It doesn't have to come together into a ball yet.
  • Add in the egg and beat until the mixture starts to come together.
  • Add in the vanilla and almond extracts and beat to combine.
  • Divide dough into portions and color with food coloring as desired, if you want different colored cookies.
  • Flatten dough into about 1/4" thick and wrap well in plastic wrap. Refrigerate for about 1 hour.
  • Preheat oven to 350 degrees F.
  • Roll out the dough to about ΒΌ" thickness. Because this dough can become soft and sticky quickly, my favorite method is to roll out between two sheets of parchment paper.
  • Dip cookie stamps into a bowl of flour to lightly coat, and then press into the dough to make designs. If at any point the dough has become too soft, place back in the refrigerator for 10 minutes or more until it firms up again.
  • Place cookies on baking sheets lined with silicone baking mats or parchment paper.
  • Bake for 9-11 minutes until edges are light brown. Remove and let cool on wire rack.
  • Decorate cooled cookies as desired.

For the cake

  • Preheat oven to 350 degrees F. Grease and flour five 6" round cake pans. Line the bottoms with parchment paper.
  • Combine cake flour, sugar, baking powder, and salt in a stand mixer fitted with the paddle attachment.
  • Add the butter and beat until a crumbly mixture forms, just starting to come together.
  • Add the egg whites one at a time, and beat to combine. Add the egg and beat to combine.
  • Combine milk and vanilla extract together in a measuring cup. Add to the mixer in three additions, beating well after each addition.
  • If you want to be precise, weigh the batter so you know divide evenly between the five pans.
  • Pour one-fifth of the batter into one of the prepared pans. Add food coloring as desired.
  • Pour another fifth of the batter into a second pan. Continue adding more food coloring as desired and pouring batter into the pans.
  • Bake for about 24-28 minutes, rotating halfway. The cakes should be set and a skewer inserted in the center should come out with a few crumbs on it.
  • Remove and place on wire racks. Run a knife around the edges for easier removal. Let cool for about 20 minutes and then invert pans to remove cakes. Let them finish cooling before decorating.

For the buttercream

  • Combine the sugar and egg whites in a medium metal bowl and place over a pan of simmering water.
  • Whisk the sugar mixture constantly over heat until the sugar is dissolved and the mixture looks smooth and shiny.
  • Continue whisking until the mixture reaches 160 degrees F.
  • Remove mixture from heat and pour into a stand mixer bowl. Whisk on medium speed for about 5 minutes until the mixture has cooled.
  • Switch to the paddle attachment and with the speed on low, add the butter a few pieces at a time, beating until smooth. Do not add the butter too quickly or beat too quickly or the buttercream may break.
  • When all the butter has been added, beat the buttercream on medium-high speed for about 6-10 minutes until it is very thick and smooth. It may appear to separate briefly but continue beating and it should come back together.
  • Add in the vanilla and almond extracts and beat to combine.
  • The buttercream is ready to be used. Place a piece of plastic wrap against the surface until you are ready to use it to prevent it from drying out.

To assemble the cake

  • Level off cake layers if necessary. Place one cake layer on a cake board or cake decorating stand.
  • Spread some of the buttercream over the cake layer evenly. Place a second cake layer on top and spread some more buttercream over the cake layer. Repeat with the remaining cake layers.
  • Refrigerate for about an hour to let the frosting set.