In a large bowl, whisk together flour, baking powder and salt.

In another bowl, using an electric mixer, beat together butter and sugar on medium-high until the mixture is light, fluffy and pale, 2 to 3 minutes. Scrape down sides of the bowl, and add eggs, one at a time, beating well after each addition. Add vanilla, and beat until everything is well combined, stopping to scrape down the bowl as needed.

Add dry ingredients all at once, and mix on low speed just until incorporated.

Scrape dough out of bowl and divide it in half. Wrap each piece in plastic wrap, patting into a 1-inch-thick disk. Chill at least 2 hours and up to 5 days.

Heat oven to 325 degrees. Roll out dough, one disk at a time, on lightly floured parchment paper or work surface until it’s about 1/8 inch thick. Create shapes, using a lightly floured cookie cutter. (Alternatively, using a knife, cut the dough into squares, rectangles or diamonds.) If at any point the dough becomes too soft to cut and cleanly remove from parchment paper, slide it onto a cookie sheet and chill for a few minutes in the freezer or refrigerator. Gather any dough scraps and combine them into a disk. Roll and repeat the cookie-cutting process, chilling as necessary.

Place shapes onto parchment-lined baking sheets 1 inch apart and bake until cookie edges are lightly browned with sandy, pale centers, 12 to 15 minutes, rotating the sheets halfway through. Cool the cookies on a rack, if you have one. Otherwise, let them cool on the pan. Decorate with a glaze, royal icing, frosting, glitter, food-grade luster dust or whatever you’d like. Don’t forget the sprinkles.

Tip #1:
Cookie dough can be made 5 days ahead and refrigerated. Cookies can be baked 2 days ahead, wrapped tightly and stored at room temperature.

Tip #2:
“Flooding” is a technique used to cover a cookie completely with royal icing. Here’s how to do it: Transfer about 1/2 cup of the royal icing to a resealable plastic bag and snip a small corner. Use this icing to pipe a thin border around the edge of each cookie. Let set for a few minutes. Thin the remaining icing with a few drops of water until it’s the consistency of syrup. Place half of the thinned icing in a resealable plastic bag and tint the rest with red and/or green gel food coloring. Transfer the colored icing to bags. Snip a corner of the white icing bag and pipe a generous amount inside the border of each cookie. Using a small offset spatula or the back of a spoon, spread the icing to cover the cookie. Decorate with the colored icing while the white icing is still wet. Let the cookies set at room temperature, at least 1 hour.