For the elderflower curd slice, first separate the eggs. Beat the egg whites with the granulated sugar until stiff. Mix the egg yolks, powdered sugar and lemon zest until foamy.
Add the vanilla pudding powder, the rasped elderflowers and the curd cheese. Carefully fold in the beaten egg whites. Line a small baking dish (approx. 22 x 28 cm) with the wholemeal butter cookies and spread the curd mixture on top.
Bake in the oven at 170 °C.
The elderflower curd slice tastes even better the next day.