Dream Swiss roll with saffron

Swiss roll is one of my favorites. This version with saffron is a dream.

3 eggs

1,5 dl sugar

1 dl potato flour

3 tbsp cacao

1 tea spoon baking powder

0,5 g saffron

1 tbsp rom

125 g butter (room temp)

1,5 dl icing sugar

1 egg yolk

1 lemon

Mix saffron and rom and leave for now. Heat up the oven to 225 degrees C. Whisk eggs and sugar fluffy. Mix potato flour, cacao and baking powder and sift into the egg mix. Put a baking paper on a tray with high edges. Pour the batter in. Bake in the oven for 5-7 minutes. Pour sugar on a tray and place the cake over with the paper upwards. Pull away the paper. If it sticks put a wet cloth over. Whisk butter and icing sugar. Add the saffron, egg yolk, a little lemon zest and some lemon juice and whisk. Cover the cake with the filling and roll to a roll.