Blueberry Roll-Up Cake

I enjoy making pretty looking cakes and today I decided to take a step further by trying out this roll-up cake that will give my guests a pleasant surprise when I cut into the cake. 

Instead of seeing horizontal layers inside, they will be surprised by vertical layers of sponge and cream. A sure way to put a smile on anybody's face! 

Hope you will enjoy making this cake as much I did!

Surprise inside cake!

Blueberry Roll-up Cake

Ingredients

Cake
5 egg yolks (medium)
50g corn oil
50g milk
20g castor sugar
85g cake flour

5 egg whites (medium)
1/4 tsp lemon juice, optional
50g castor sugar

Blueberry sauce
100g blueberries
30g sugar
1/2 tsp cornflour
pinch of salt
30ml water
1/2 tsp lemon juice, or to taste

For decoration
450ml dairy whipping cream/heavy cream
4-5 Tbsp icing sugar, or according to taste
almond flakes, lightly toasted

Method

1) To make the blueberry sauce, place the sugar, cornflour, salt and water in a small saucepan and stir until smooth.

2) Gently stir in the blueberries and place the saucepan over medium heat.

3) Cook (simmer) the sauce until the liquid thickens and becomes clear, stirring gently occasionally (about 10 mins). Some of the blueberries will break down but others will remain whole. The longer you cook the sauce the thicker it will become (if sauce is still too thin, add a little cornflour diluted in a bit of water to help thicken the liquid).

4) Remove from heat and stir in the lemon juice. Taste and add more if needed. Set aside to cool completely.

5) Line a 10" x 13" swiss roll pan with baking paper. 

6) To make the cake, lightly whisk egg yolk with sugar (20g). 

7) Add in corn oil and stir to combine. Next, add in the milk and combine well.

8) Fold in the cake flour, mix well and set aside.

9) Add lemon juice to the egg white and beat until foamy. Gradually add in sugar (50g), and beat until stiff peak and glossy.

10) Take 1/3 portion of the egg white mixture and using a handwhisk, mix with the egg yolk mixture until light. With a rubber spatula, gently fold in the rest of the egg white mixture until well incorporated.

11) Pour the batter into the prepared pan and smooth the top to level evenly. 

12) Bake in the preheated oven at 160C for 25 mins or until it springs back when lightly touched. 

13) Cool the cake on a wire rack until it reaches room temperature.

14) Meanwhile, prepare the cream filling by beating the whipping cream until thick. Add in sugar and whisk until firm. 

15) For the blueberry cream, scoop about 1/3 of the whipped cream into a bowl and add in some of the blueberry sauce and mix well until you get an even blue coloured cream. (If not using immediately, place the whipped cream in the fridge until needed).

16) To assemble the cake, place it on a clean piece of baking paper (same size as the cake). 

17) Cut the cake with a serrated knife into four equal pieces.

18) Cut through the underlying baking paper with a pair of scissors in the same places that you cut the cake.

19) Spread a layer of blueberry cream on one of the strips. 

20) Using the baking paper as support, tuck the cake into a roll and continue tucking and rolling until you get a small neat roll. Place the rolled cake upright on a serving plate, so that the spiral of cake and filling is visible at the top.

You might want to apply a thinner layer of cream at the
 center of the roll as I think I applied a bit too much!

21) Apply cream filling to the next strip and lift it up using the support of the baking paper and wrap it around the roll on the serving plate, continuing from the edge where the first roll ended.

22) Continue with the next two strips, to make one big rolled up cake.

You can neatly trim off the end of the last strip to make the cake look rounder

23) Finish by frosting the sides and top of the cake with the whipped cream. Spoon the blueberries and sauce (not too much liquid) on to the middle of the cake. Pipe out dots of cream around the circle of blueberries. Stick the almond flakes onto the sides of the cake.

24) Refrigerate the cake until ready to serve.