http://vintagetrinkets.blogspot.kr/2012/10/purple-sweet-potato-roll-cake.html
| Filling： | |
| 300ml whipping cream | |
| 3 tbsp icing sugar | |
| 1 tsp vanilla paste |
Add cream and sugar in a medium bowl, put it into a bigger bowl filled with iced water. Whisk the mixture until firm peak forms.
1 purple sweet potato, diced leftover purple sweet potato cream (recipe here)
Remove liner from the cake. Transfer the cake onto a piece of parchment paper with the baked side facing upwards. Spread the filling evenly on the sponge base (leaving about 2/3 - 3/4 cup of cream filling aside). Place the diced sweet potato on top of the filling. Roll the cake up and with then tuck in both ends of the parchment paper. Put the roll into the fridge to chill and set. After half hour, spread the remaining cream filling onto the outside of the roll. Return to fridge to chill for a few hours.
Place purple sweet potato in piping bag with Wilton multi-opening decorating tip attached and pipe purple sweet potato cream onto the top of the cake. Sift snow powder right before serving and top with purple sweet potato slices (optional). Slice and serve.