Beat the butter for two minutes in a kitchen machine.

Add the egg, sugar, bourbon vanilla sugar and salt and beat until pale.

Stir in the flour until you have a smooth dough.

Form the dough on a well-floured working surface to a long roll with a diameter of 5cm/2in. Wrap the roll in a baking paper and let it chill for one hour in the fridge. Cooling the dough makes it easier to cut it later.

Preheat your oven to 200°C/390°F (conventional).

Place your chilled dough-roll on a cutting board and cut about 1cm/0.4in thick cookies. Put them on a with baking paper lined baking sheet. The cookies should have enough space. Therefore it's better to use two baking sheets.

Bake your cookies for 10 minutes in the middle of the preheated oven. If you use two baking sheets, bake one after the other.

Let them cool down on a cooling rack.

Mix 200g icing sugar with three tablespoons of lemon juice. Only add one tablespoon after the other to the icing sugar to make sure that the glaze doesn't get to thin.

Divide the glaze into three little glasses. One remains white for the decoration, and with the other two, you will make the pastel color. To get the pastel color, it doesn't need a lot of the food coloring. Therefore, add just one drop at a time to the glaze, mix it and repeat this until you reach the color of your desire. To get a mint green as I did in the picture, you need to combine the blue and green food coloring 1:1. If your glaze gets too thin after adding the food coloring, just mix in some more icing sugar.

Pour half a teaspoon of the pastel glaze on each cookie and spread it smooth with the back of the spoon.

Let the colored glaze dry for 10 minutes.

To decorate the cookies, place the white glaze in a plastic freezer bag and cut away a very tiny hole at one edge. Now, you have a simple and cheap icing bag. Decorate your cookies and let them dry for another 10 minutes. Be creative! You can store your butter cookies with the pastel glaze up to one week in a cookie box.