In a mixing bowl, sift the flour, baking powder and salt together.
In another large mixing bowl beat the butter and sugar together until pale and fluffy. Add the egg and vanilla, mix until combined. Gradually add the flour mix in a little at a time, mix until dough is formed.
Preheat the oven to 325°F. Line baking sheet(s) with parchment paper or silicone baking mat.
Roll the dough out onto a lightly floured surface to about ½ cm thick. If the dough is too sticky to roll out, shape into disc and cover in plastic wrap and chill for 20 minutes. Once dough is rolled out, cut out cookies and transfer to baking sheet(s). Roll up remaining dough and repeat steps until all dough is used up. Chill the raw cookies on the baking sheet(s) in fridge for 10 minutes before baking. This helps the cookies retain a nice crisp shape during baking.
Bake cookies in preheated oven for 8-12 minutes until just golden at edges. Let cool for a few minutes on trays before transferring to cooling rack to cool completely before icing.
To make the icing, add icing sugar to a large mixing bowl. Gradually add half of the water, mixing well. Add in the corn syrup and almond extract, mix well. If the icing is too thick, add a bit more water, one teaspoon at a time. Divide icing into several small bowls, depending on how many different colors you want. Tint each bowl of icing with food coloring. If your icing is thick enough try spooning small amounts onto each cookie and spreading around to cover the cookie. Adjust consistency of icing with more water if too thick or more icing sugar if too runny. While cookies are still wet decorate with sprinkles of your choice. You can also fill piping bags or small plastic bags with icing and cut a tiny whole out of the corner to use like a piping bag, have fun decorating your cookies!