To the cooled butter and honey, add the egg and beat everything. Add the flour gradually while stirring. If needed, add more flour.
You need to obtain a soft butter dough. Roll the dough out onto a floured surface into a 1/4" thick sheet. Cut out the desired figurines using cookie cutters.
Arrange the doughy figurines in a tray laid out with baking paper. Bake in a preheated 356°F (180 °C) oven until their edges begin to brown slightly.
Decorate the baked cookies with royal icing. To make it, put the egg white in a bowl.
Beat it until it starts to foam. Then add 1 tbsp powdered sugar at a time, in lots. Continue beating until it absorbs all of the powdered sugar, while also adding the lemon juice.
Optionally, you can color the royal icing with confectionery dyes.