Chocolate Purple Sweet Potato Roulade

I could feel the breeze on my face, it was bending branches in the trees. I woke up to my amazed to see the rabbit dressed and had a watch, ran by at full speed, muttering "I'll be late!". There were colourful flowers in the countryside, a sleepy-looking caterpillar laid on a giant toadstool, a cat curled up on the tree's branch.

The Queen of Hearts ate the log with purple swirl without hesitating! What?! ...yes, you are in the Wonderland.

Manage to get a copy of 孟老师's roulade recipes from Kinokuniya, swing into action as I have been long wanting to bake her roulade. For the sponge I'm using the recipe for Chocolate log that used France Style Egg Separation Method 法式分蛋海绵蛋糕。As the filling I'm using her method for Yam Swiss Roll as it doesn't require to whisk the whipped cream, this really save me time on cleaning up :)   

The texture of this roulade is difference from my previous roulades because of the method and almond powder used. The sponge is soft and dense, the taste is better with almond. Oh, dear! time to wake up from my wonderland.  

Recipe adapted from 孟老师 with changes to the filling.

Ingredients for cocoa batter:

25g butter

20g icing sugar

25g egg whites

20g top flour

5g cocoa powder

Steps:

1. Soften the butter, mix with all ingredients.

2. Pour on baking tray, use a scraper to smoothen the cocoa batter.

3. Use comb scraper to comb out the line pattern on batter. Place in freezer for 30 mins. 

Ingredients for purple sweet potato filling:

250g purple sweet potatoes (peeled, steamed and mashed)

50g icing sugar

30g butter

50g whipping cream

Steps:

1. Add icing sugar and butter to the mashed purple sweet potatoes while it's hot. Use a spatula to stir well.

2. Gradually add the whipping cream into the purple sweet potatoes and mix until it is smooth. Set aside in fridge for 30 mins.

Ingredients for sponge:

20g butter

60g almond powder

30g icing sugar

120g eggs (about 2)

100g egg whites (about 2.5)

60g fine sugar

50g top flour

Steps:

1. Melt the butter.

2. Whisk the almond powder, icing sugar with full egg until the batter turned pale.

3. Beat egg whites until frothy, add 1/2 sugar and beat until soft peaks. Put in remaining sugar gradually and beat until stiff.

4. Fold ¼ of egg whites into (2) and then another ¼ egg whites.

5. Pour egg batter into the remaining egg whites and fold (no need to be too thorough).
6. Shift in the flour in two batches, fold well.
7. Pour small amount of the flour batter into (1), mix well and pour the butter batter into the remaining flour batter, fold until well combined.
8. Pour into baking tray and bake at 190C for 12~15 mins.
9. Remove the sponge from tray once the sponge is out from oven. Let it cool completely before apply the filling.
10. Roll up the sponge in swiss-roll style and place in firdge for at least 1 hour before cutting the edge.

I'm submitting this post to Natural Colour Bakes hosted by Hankerie.