Purple Sweet Potato Mousse Swiss Roll 紫薯仔慕斯瑞士卷

I bought a kilo of purple sweet potatoes a few days back and not sure what to make...... I used half of them to make six flavour tong sui dessert and still have another half kilo left sitting there. Oh well, I wanna to make something quick and simple, so that I can go aftering my K drama later on.... haha.... Finally, decided to make sweet potato mousse which is easy to prepare. On the other hand, bake a quick sponge and Swiss roll is the best choice cause no need cake dividing or things like that. Just spread and roll it up. And then end of the story ...... haha.... Oh mygoodness .... haha...  Please read on for more.

Ingredients for Sponge Cake :
(A)
4 egg yolk
20gm  fine sugar
60ml   milk
40ml   corn oil
70gm  cake flour/all purpose flour
1 tspn  vanilla extract/essence

(B)
4 egg white
50gm  fine sugar
1/4 tspn  cream of tartar

Method :
(1) from ingredients (A), hand beat sugar and egg yolk till creamy, then add in flour and milk alternately with  in 3 batches till everything well cooperated. Then stir in oil & vanilla and Set aside.
(2)  Ingredient (B), whisk egg white till foamy then add in cream of tartar and half of the sugar. Continue beating till thick & foamy. Add in the remaining sugar and beat till top foam.
(3)  now, fold meringue into mixture (A) till everything well blended. Do not over mix.
(4)  transfer batter to a 9x11" baking tray lined with parchment paper.
(5)  finally, bake at preheated oven 180'C for 25 minutes.
(6)  once its done, unmould cake with placing a wax paper or non-stick baking paper over the surface of the cake then top with another layer of kitchen towel or silicon sheet, flip over the cake. This is to prevent the cake surface from sticking to the sheet while removing it later.
(7)  remove baking paper then roll cake together with the silicon sheet or kitchen towel, into swiss roll while its still warm. Leave it to cool down in rolled shape.

Ingredients for Sweet Potato mousse :
500gm   purple sweet potatoes
200gm   butter, diced
100ml    whipping cream

Method :
(1)  skinned sweet potatoes then sliced into small pieces and then steamed for 15 mintues.
(2)  once its ready, mashed into puree then stir in butter chunks till everything well cooperated.
(3)  next, press sweet puree through a fine sieve and discharged any remaining chunks.
(4)  whipped cream till set then fold into sweet potato puree till well combined.
(5)  finally, transfer mixture to 2 different pipping bags.

TO ASSEMBLE :
(1) once the cake has cooled, unroll the cake as picture shown below.

(2)  now, pipe in the sweet potato mousse and then spread evenly with a plastic gadget as picture shown below.

(3) Finally, carefully roll it up into Swiss roll as picture shown below.

(4)  now, decorate the Swiss Roll with the remaining sweet potato mousse as your own preference.

Finally, keep chilled and serve.  Sinfully delicious ! Love it so much.