In a separate bowl, add baking flour and icing sugar. Mix until combined.
Make a hole in the middle of the flour and pour in the softened butter and one egg.
Stir and then knead the dough until well integrated.
Roll a ball with the dough, wrap it in cling film and put it to chill in the freezer for 10 minutes.
Once chilled, roll the dough out to 1/5 inch thick.
Preheat the oven to 360º F (180º C).
Line up a baking sheet with parchment paper and place on top the figures you have made with the cookie cutters.
Bake for 10 minutes or until they are golden brown. Allow cookies to cool for 10 minutes and then transfer them to a wire rack to cool completely before decorating.
Roll out the fondant with the help of a rolling pin to 1/8 inch thick. Use the same cookie cutters you have used before and, with the help of a brush and a small glass of water, moisten a little the fondant before sticking it to the cookie. Repeat this process with all your cookies. Et voilà! You have just made amazing decorated butter cookies!