biscuits with almonds and cinnamon

ingredients:
150 g butter, softened
100 g caster sugar
200 g of wheat flour
1 egg
1/2 teaspoon cinnamon
30g icing sugar
50 g whole almonds
method :
1. In a bowl, mix the softened butter and sugar. Add flour and cinnamon, mix well then add an egg yolk and 15 g of cold water. Mix the dough, it will be a little sticky.
2. Place the dough between 2 sheets of parchment paper and spread it with a rolling pin into a square about 20 x 20 cm.
3. Mix half the egg whites with the remaining icing sugar and brush the paste mixture.
4. Grind the almonds and spread them on the sand.
5. Bake 20 minutes in preheated oven at 180 ° C.
6. Remove from the oven, cut the shortbread into 16 pieces. Let cool before serving.
http://www.odelices.com/recette/janhagel-petits-sables-hollandais-aux-amandes-et-cannelle-r3228/