For the dough, use a stand mixer and attach the whisk. Add the butter to the mixing bowl and whisk until creamy. Then add the powdered sugar and combine. 

Add the egg yolk and whisk again. Then add the salt, vanilla extract and lemon juice. Mix until incorporated.

Remove the whisk and add the dough hook. Lower the speed and stir in the almond flour and the sifted all purpose flour. Mix until a dough forms. 

Wrap in plastic foil and place in the fridge for 1 hour.

Preheat the oven to 180°C. Cover a baking tray with baking paper.

Take the dough out of the fridge and roll out (0,5 cm thick) on a lightly floured surface. Cut out the cookies using a heart shaped cookie cutter. Use a smaller hearts shaped cookie cutter to cut the middle of half of the cookies. Transfer them on the baking tray. 

Place in the oven for 8 minutes until they look dry. Let them cool completely on a cooling rack. 

Dust the cookies with the cut outs with powdered sugar. Spread the Biscoff spread on the whole cookies. 

Place a cut out cookie on top, press lightly and serve!