Whether you refer to the technique as Japanese roll cake or joconde imprime cake, this easy technique of inlaying designs in a thin layer of batter is taking the baking world by storm. With lines in various widths forming the design, you can learn this innovative technique with guidance from our how-to video. Sponge cake has never been more beautiful!
Prepare pan and batter. Preheat oven to 350°F. Line jelly roll pan with parchment paper. Lightly spray parchment paper with non-stick spray and wipe with paper towel to evenly spread and absorb excess spray.
Prepare sponge cake batter following recipe directions.
Tint batter. Measure out approx. 1/2 cup of batter. Sift cocoa powder into 1/2 cup batter. Fold in gently. Place batter in a disposable decorating bag and tie with icing tie to prevent spillage.
Measure out approx. 1/2 cup of batter. In separate bowl, place a small amount of batter and stir in rose icing color, making a darker shade. Gently fold tinted batter back into the 1/2 cup of batter. Place batter in a disposable decorating bag and tie with icing tie to prevent spillage.
Pipe inlays. Cut decorating bags approx. 1/8 in. from tip (or more for wider stripes). Alternating bags so stripes overlap, randomly pipe lines in crisscrossing pattern on parchment paper-lined pan until all batter is used. Bake 2 minutes.
Make cake. While stripes are baking, use icing colors to tint 2 tablespoons of remaining batter green, making a darker shade. Gently fold tinted batter into remaining batter. Carefully pour green batter over baked stripes. Use spatula to evenly distribute batter in pan.
Bake cake 10 to 12 minutes. Cool in pan 10 minutes, then loosen the sides of cake from pan edge. Turn out of pan onto a second piece of parchment paper. Gently peel off parchment from pan and turn cake back over. Starting at short end, roll cake so pattern shows on outside and cool completely.
Fill cake. Prepare chocolate buttercream icing following recipe directions. Gently unroll cooled cake. Use spatula to spread 1 1/2 cups icing on cake. Reroll cake and cut ends of roll for a clean edge.