In a food processor add all dry ingredients: almond flour, all purpose flour, baking powder, sugar and lemon zest. Pulse a few times. Add cold butter cut in cubes. Pulse until you get a crumbly dough.
Mix in an egg and finally lemon juice (approx ¼ cup).
Knead briefly until all ingredients are well combined. Don’t knead for too long as butter will start to melt.
Cover the dough with a plastic wrap and let rest in the fridge for 20-30 minutes.
Preheat the oven to 375F.
Cut of a piece from the dough ball.
Roll it into a rope approx ½ inch thick. Cut the rope into ½ inch pieces.
Quickly roll each piece between the palms forming a ball shape and roll it in powdered sugar.
Place on a baking sheet lined with parchment paper. Bake for 10-12 minutes in a preheated to 375F oven.
The cookies should mostly remain pale and only brown lightly on the edges.