Springtime Rhubarb Roll Cake

Rhubarb jam and a light mascarpone cream fill this deliciously spiced sponge cake roll.

You also have the option to add fun or fanciful designs to the outside of your cake.

Heather’s Springtime Rhubarb Roll Cake helped her win Star Baker for Cake Week in Season 7 of The Great Canadian Baking Show.

Springtime Rhubarb Roll Cake

By Heather Allen

Ingredients

Rhubarb Jam:

• 3 cups (360 g) chopped rhubarb
• 1 cup (200 g) sugar
• 1½ tsp lemon juice
• ¼ cup water
• Pinch of salt

Sponge Cake:

• 6 tbsp plus 1 tsp (43 g) cake flour
• 3 tbsp cornstarch
• 1 tbsp cocoa powder
• ½ tsp cream of tartar, divided
• ¼ tsp salt
• ½ tsp nutmeg
• ½ tsp ground ginger
• ½ tsp cardamom
• ½ tsp cloves
• Pinch of ground black pepper
• 1½ tsp molasses
• 1 tsp vanilla extract
• ½ tsp almond extract
• 6 eggs, room temperature, divided
• ½ cup plus 1 tbsp (95 g plus 12 g) superfine sugar, divided

Rhubarb Mascarpone Cream Filling:

• 1 cup 35% cream
• ¾ cup (85 g) icing sugar, more or less, to taste
• ¾ cup (170 g) mascarpone cheese
• ¾ cup (90 g) freeze-dried rhubarb powder, optional
• Pinch of salt
• ½ tsp almond extract

Pattern Paste (optional):

• 2 tbsp plus 2 tsp cake flour
• 5 tsp superfine sugar, divided
• 4 tsp whole milk
• 1 tsp canola oil
• 2 egg whites
• Gel food colouring, optional

Preparation

Rhubarb Jam:

Add all ingredients in a large saucepan. Cook over medium-low heat, stirring occasionally for about 15 to 20 minutes, until the rhubarb has broken down. If lumps remain, mash with a potato masher or fork. If you prefer it more smooth, cool slightly and use an immersion blender to puree the mixture.

Set aside to cool completely.

Pattern Paste (optional):

Prepare if you are adding a decorative design on the outside of the roll.

Lightly spray an 11-by-17-inch jelly roll pan with cooking spray. Line the pan with parchment paper, overlapping the short ends over the edge of the pan slightly. 

In a medium bowl, whisk together the flour, 2 teaspoons of superfine sugar, milk and oil to form a paste.

In a seperate bowl, whip egg whites with a hand mixer until frothy. Sprinkle the remaining superfine sugar overtop and whip until soft peaks form. Gradually stir the mixture into the paste, one-third at a time, until fully incorporated. 

If colouring the paste, divide it into bowls and colour as desired using the gel food colouring. Place each colour into piping bags and snip off the ends. Draw the desired pattern on top of the parchment paper in the prepared pan. Remember to draw your pattern in reverse, if necessary! Place the pan in the freezer until the cake batter is ready.

Sponge Cake:

Heat oven to 450 F. Lightly spray an 11-by-17-inch jelly roll pan with cooking spray. Line the pan with parchment paper, overlapping the short ends over the edge of the pan slightly.

Note: If you have prepared a design for the outside of your roll, use that pan.

In a bowl, whisk together cake flour, cornstarch, cocoa powder, ¼ teaspoon cream of tartar, salt and spices. In a separate small bowl, stir together the molasses, and vanilla and almond extracts. Set aside.

Place 4 whole eggs and 1 egg yolk in the bowl of your stand mixer bowl. Add ½ cup superfine sugar and whisk on high until the eggs fall off the whisk in thick ribbons, 3 to 4 minutes. Add the molasses, vanilla and almond extract mixture. Sift in the dry ingredients and fold together gently, until no streaks remain.

In a medium bowl, combine the remaining 2 egg whites and remaining ¼ teaspoon cream of tartar and whisk with a hand mixer on high until soft peaks form. Sprinkle 1 tablespoon superfine sugar overtop and whisk again until stiff peaks form. Set aside.

Add about a quarter of the egg white mixture to the batter and mix to combine, using a whisk if needed to combine and loosen the batter. Gently fold in the remaining egg white mixture until no streaks remain, being careful not to deflate the batter.

Gently pour your cake batter over the middle of your prepared pan, pouring close to the pan to avoid deflating the batter. Using an offset spatula or butter knife, gently push the cake batter over the pattern mixture, if necessary, again being careful not to deflate.

Bake until the top is evenly brown, about 8 minutes.

Once baked, use the overlapping parchment to slide the cake off the pan onto a wire rack and let cool for 5 minutes. Place a piece of parchment paper (same size as pan) on the counter. Flip cake onto fresh parchment and peel off the used sheet.

Place the used parchment paper over the cake with the clean side touching the cake and flip the whole thing back over. If your cake has a pattern, it should be facing down. Score the plain side of the cake gently crosswise about 4 times, being careful not to cut all the way through. Starting at a short end, gently and slowly roll up the cake. Wrap in a clean kitchen towel and place, seam side down, in the fridge to cool.

Rhubarb Mascarpone Cream Filling:

In a large bowl, whip cream and icing sugar with a hand mixer on medium-high until soft peaks form. Set aside.

In a medium bowl, use the same hand mixer and blades to whip the mascarpone, rhubarb powder, if using, and salt together. Stir in almond extract.

Note: If using rhubarb powder, the mixture may become stiff. If so, drizzle in some extra cream, 1 tablespoon at a time, adding no more than two tablespoons. 

With your hand mixer running on low, add the mascarpone mixture to the whipped cream, one spoonful at a time, until fully incorporated. Transfer to a pastry bag and cut the tip to make a hole about 1 cm wide.

Assembly:

Unroll the cooled cake gently. Remove top parchment paper. 

Spread a 3-mm-thick layer of the rhubarb jam over the inside of the cake. 

Pipe the mascarpone cream in lines about 1 cm apart along the long side of the cake. Starting at a short end, gently roll the cake, using the parchment to help. Place on a platter, seam side down, and refrigerate until ready to cut and serve. If leaving whole for presentation, you can trim the end to expose the pretty swirl.

Makes one roll cake