Greek yogurt cake roll

Although I am not a big fan of Valentine's day, this year I decided on a Valentine's theme, since it was weekend anyway and I was baking as usual. It was also a chance to try this heart design on a cake that I saw on pinterest. 

For the hearts:
1 egg
30 g sugar
40 g flour
20 g butter
food colouring

For the roll dough:
2 eggs
60 g sugar
40 g flour
10 g corn flour
40 g butter
pinch of salt

For the filling:
340 g greek yogurt
250 g mascarpone
1 vanilla bean
1 tbsp of confectioners sugar
fruit of your choice

Ingredients are enough for one baking sheet (mine is 30 cm x 37 cm), but the dough will not be very thick. If you like it thicker, than add an egg and increase the other ingredients by a third.

Separate one egg and save the egg yolk for later. Mix the egg white with the sugar and flour to get a thick batter.

Mix in the softened butter and in the end a bit of food colouring. Put the batter into a decorating bag with a small round tip or just cut the tip of the decorating bag.

The smaller the tip, the easier is to be more precise and the hearts will look more beautiful. My tip was a bit too large and the hearts came out less neat. Yeah well, it will be better the next time... Hearts are easy to pipe freehand, but if you find it easier just put a stencil under the baking paper.

Put the pied hearts into the freezer for an hour or so. You only need to pipe a half of sheet of hearts, enough to cover the outside of the roll.

For the rol dough mix the flour, corn flour and salt in a bowl. Put the sugar and the eggs, together with the egg yolk, saved from before, into a heat proof bowl and set it over a pot of boiling water. Mix the eggs over the steam, so that the sugar dissolves completely and the eggs become luke warm.

Pour the mixture into the mixer bowl and beat at high speed for 5 minutes. The mixture will rise significantly and lighten in colour. Add the flour mixture and fold in carefully.

Melt the butter and ti it in the batter until fully incorporated.

Heat the oven to 200° C. Take out the frozen hearts and pour the batter over them and spread it gently over the sheet.

Bake for 8 minutes.

Once baked, immediately and carefully (! really carefully the cake is really delicate) remove the baking paper and set the sheet cake dough on a kitchen towel  and roll it, so that the heart print is on the outside.

Use a real Greek yogurt for the filing since it is thick and you will not need gelatin for the filling.

Mix the yogurt, mascarpone and vanilla bean seeds with a spoon of sugar (or more if preferred). Take the sheet cake from the towel and spread  the filling over the sheet cake. Add chunks of you favourite fruit (in my cake apricots) and roll back into a roll.