Ingredients
Equipment
Method
- Line two baking sheets with parchment paper and set aside.
- Whisk together flour, baking powder, and salt in a medium bowl and set aside.
- Cream butter and sugar in a stand mixer or with a hand mixer until completely smooth.
- Add the egg and mix until combined, then add the vanilla and mix again.
- Add the dry ingredients and mix until a dough forms and pulls away from the sides of the bowl.
- Wrap the dough in plastic wrap and refrigerate for 45 minutes, or up to three days.
- Preheat the oven to 350°F. On a lightly floured surface, roll the dough to just under 1/4 inch thick.
- Use a bench scraper or knife to cut 3x5-inch rectangles from the dough. Re-roll scraps and repeat.
- Place cookies at least one inch apart on prepared baking sheets and refrigerate for 10 more minutes.
- Bake for 12 to 14 minutes, until the bottom edges are just starting to turn golden brown.
- Transfer sheets to a wire rack and allow cookies to cool completely before frosting.
- For the buttercream, sift and weigh the powdered sugar, then beat with softened butter until smooth. Add salt and vanilla, then beat on medium-high for 4 to 6 minutes until light and fluffy.
- Fill a piping bag fitted with a small round tip (Wilton 10 recommended).
- Pipe a square in the top left corner of each cookie and press in blue star sprinkles.
- Pipe four horizontal lines across the cookie to form the stripes.
- Add red sprinkles to every other stripe, tap off the excess, and repeat for the remaining cookies.
Notes
Chill the dough thoroughly before baking to help the cookies maintain their rectangular shape. Sift powdered sugar before making buttercream for smooth piping. For a royal icing style finish, substitute the buttercream with traditional royal icing. Baked unfrosted cookies can be frozen for up to 2 months.