In a bowl, combine the flour, ground ginger, ground cinnamon, and baking soda.

In another bowl, cream together the softened butter and brown sugar until smooth.

Add the molasses, egg yolk, and vanilla extract to the butter mixture, mixing until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.

Roll the dough into balls and flatten them slightly. Place them on a baking sheet.

Bake in a preheated oven at 350°F (175°C) for 10 minutes or until just set.

Allow to cool, then decorate with royal icing and sprinkles or edible glitter.