Preheat the oven to 160 °C convection oven for the poppy seed and hemp biscuits. Beat the egg whites with the sugar, lemon juice and a pinch of salt until foamy. Mix in the ground poppy seeds, the hemp flour and the grated lemon zest.
Pour the poppy seed and hemp mixture into a piping bag and pipe the biscuits onto two baking sheets lined with baking paper. Bake in the hot oven for 20 minutes, one after the other, then let cool.
Spread 1/2 tsp fruit spread on half of each biscuit and stick together with a second biscuit.
Sprinkle the poppy seed and hemp biscuits with powdered sugar.