For the vanilla shortbread:

170g of flour
70g of icing sugar
100g of butter
1 egg
½ teaspoon of vanilla powder

For the chocolate sablée pastry:

170g of flour
25g of cocoa powder (unsweetened)
70g of icing sugar
100g of butter
1 small egg

Preparation:

In a bowl, mix the flour, icing sugar and vanilla powder.
Add the cold butter cut into cubes. Work the mixture with your fingers until you obtain a sandy consistency.
Set the mixture aside.
In another bowl, beat the egg with a fork.
Pour half the beaten egg into another bowl that you will use later in the recipe.
Add the previously sifted cocoa to the rest of the beaten egg. Mix well.
Incorporate the colored beaten egg into the chocolate mixture.
Work the dough obtained with your hands until it forms a homogeneous ball. Repeat the same operations for the vanilla dough.
Wrap each ball of dough in cling film and refrigerate for about 1 1/2 hours.
After resting, roll both doughs into two large rectangles of similar size on a floured surface.
Gently lift the orange dough and overlap it with the cocoa dough, turning it.
Press the two doughs together well and roll the dough across itself across the width.
Wrap the roll of dough in cling film and place in the freezer for about 30 minutes.
Preheat the oven to 170 degrees Celsius.
After resting in the freezer, cut slices approximately 6-7 mm thick with a sharp knife.
Arrange the slices on baking trays lined with baking paper.
Bake for about 12 minutes. The biscuits should not be too colourful.
Let cool completely before enjoying. Enjoy your meal!