Preheat oven to 180 °C (convection oven).
Preheat oven to 180 °C (convection oven).
Insert the mixing attachment into the mixing bowl. Add egg whites with a pinch of salt and half of the confectioners' sugar to mixing bowl and whip without measuring cup for 7 minutes/step 3.5. Remove the whisking attachment and pour the beaten egg whites into a large bowl.
Replace the whisking attachment. Cream the butter with the remaining powdered sugar, vanilla sugar and the QimiQ Cream Base for 3 min./60°C/step 1.5 until smooth.
.Add the curd, egg yolk, lemon juice and lemon zest and whisk for 10 sec./speed 3. Remove the whisk attachment.
Combine the flour with the baking powder, add to the mixing bowl and stir for 15 sec/step 3.
Gently fold the mixture into the beaten egg whites and stir.
Pour into the greased loaf pan and bake for about 35 minutes.
Let cool and decorate with sugar icing as desired.