Put butter at room temperature in a large bowl, add both types of sugar, salt, egg and flavor to it.
Beat well with a mixer (3-4 minutes at high speed).
Add color to the mixture and mix thoroughly.
The amount of dye is indicated approximately, be guided by the manufacturer's recommendations and the desired shade.
Measure out the flour.
Mix flour with baking soda and baking powder.
Sift flour mixture and cocoa powder into a bowl of liquid ingredients and stir.
Should have a sticky and thick dough.
Wrap the dough in plastic wrap and refrigerate for at least 1 hour, maximum 24-48 hours.
Remove the dough from the refrigerator, roll it into balls.
I got 20 balls weighing 30 g each.
Place the balls on a baking sheet.
Bake in an oven preheated to 180 ° C for 11-14 minutes.
Cool the cookies on a baking sheet for about 5 minutes, then transfer them to the wire rack and allow to cool completely.
For decoration, melt white and / or dark chocolate and dip each cookie halfway into it.
Decorate with pastry sprinkles on top, place on a plate or wire rack and let the chocolate harden.