This is the sugar cookie recipe I always use when I need cookies to decorate or I'm baking with a bunch of kids. It's a super-easy recipe that makes delicious cookies for any time of the year. This is also a great starter recipe to get kids baking.
Technique tip: Put the butter on the counter the night before so it is soft when you're ready to bake.
Swap option: Brown the butter in a pan over low heat for about 10 minutes to give the cookies a toasty, nutty flavor.
Special equipment: Cookie cutters and piping bags.
For the cookies:
Preheat the oven to 375°F. Line a baking sheets with parchment paper.
In a big bowl, combine the butter, sugar, salt, cinnamon and vanilla and mix until smooth and fluffy. Stir in the baking powder, taking care to mix well. Add the eggs and egg yolk and stir well. Add the flours and gently stir until a smooth ball forms. Wrap the dough in plastic and put in the fridge for at least 1 hour.
On a floured surface, roll out tennis ball-size pieces of dough to about 1/4-inch thick and cut out the shapes you want. Lay them on the prepared baking sheet, leaving at least 1/4-inch between each cookie.
Bake for 8 minutes, or until lightly golden.
Transfer cookies to a wire rack and let cool.
For the royal icing:
Using a stand mixer and the whisk attachment (or an electric mixer), whip all the icing ingredients together. Whip for 5 to 8 minutes, or until the royal icing holds its shape and is bright white (not translucent). If it is too soft, add more powdered sugar.
If it is too stiff, add a bit more water, one drop at a time. If you are using only one color, add a few drops of the color at this point and keep whipping until you have the shade you want; otherwise, separate the icing into small bowls for each color, add the food coloring to each and mix well.
Transfer the icing to piping bags.
For the assembly:
Decorate the cookies with the royal icing. Add the sprinkles quickly before the icing sets.
Allow the icing to dry fully before serving.