Place the flour in a fountain and add in the center all the ingredients for the pastry: sugar, eggs, butter in chunks, grated peel and bicarbonate.
Mix the ingredients quickly until the dough is compacted, then coated with plastic wrap and let stand in the fridge for at least 30-60 minutes.
Take back the pastry, roll out with a rolling pin and get the half hearts and pieces of the puzzles
As they are ready, place them on a baking sheet covered with baking paper.
Bake in preheated oven at 180 ° C for about 15 minutes or until the edges start to brown. Then take out and let it cool.
Roll out the sugar paste into a thin sheet and cut the half hearts with the same molds used to make the biscuits.
Prepare the icing to the water and brush the biscuits and then attach the sugar paste decorations.
With the remaining icing, stick the hearts of sugar: when the glaze is dry, the puzzle biscuits will be ready.