Matcha

1. Separate the eggs. Beat the egg whites until stiff, adding 30g sugar. Pour the hot water into a bowl with the Matcha and stir thoroughly until the Matcha has dissolved. Beat egg yolk with water, vanilla sugar and remaining sugar for at least 5 minutes until foamy. Add the egg whites to the egg yolk mixture. Mix flour, cornflour and baking powder and sieve over the egg white mixture. Carefully fold in the flour mixture with a dough scraper. Place the mixture on a baking tray lined with baking paper. Bake in a well preheated oven at 190° (170° convection) for 12-14 minutes. The bottom of the cake should be firm to the touch.
2. Immediately after baking, turn the sponge roll onto a piece of baking paper sprinkled with sugar. Remove the baking paper and roll up the sponge cake immediately. Wrap in a tea towel to cool down. 
3. For the filling, wash the limes, then dry and rub the peel of 1½ of the limes. Squeeze the juice of all 3 limes (60ml juice). Mix the lime juice and peel with sugar. Mix the cream cheese and mascarpone briefly until a smooth mixture is obtained. Whip the cream until stiff, stirring in 1 sachet of cream stiffener. Add the cream to the mixture.
4. Unroll the sponge roll. Spread the cream on the sponge dish. Sprinkle with blueberries and then roll up the sponge again using the baking paper. Refrigerate the roll for about 30 minutes. 

Preparation time: 1 hour (without baking and cooling time)