Instructions:
- In the bowl of a mixer, beat the softened butter and granulated sugar until light and fluffy (about 3 minutes). Scrape down the sides.
- Beat in the vanilla extract until just combined.
- In a separate bowl, whisk together the flour and salt.
- Gradually add the dry ingredients to the wet mixture on low speed. Mix only until the dough just starts to come together—do not overmix.
- Gently fold in the rainbow sprinkles using a spatula until evenly distributed.
- Divide the dough in half. Form each half into a flat disc, wrap tightly in plastic wrap, and chill for at least 60 minutes.
- Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
- On a lightly floured surface, roll out one disc of chilled dough to about 1/4 inch (6mm) thickness.
- Use cookie cutters to stamp out shapes. Gather scraps, gently re-roll, and place shapes onto the prepared baking sheets, about 1 inch apart.
- Bake for 14–18 minutes, rotating halfway through, until the edges are just beginning to turn a very pale gold.
- Let cookies cool on the baking sheet for 5 minutes before transferring them carefully to a wire rack to cool completely.
- Dust lightly with powdered sugar or press a few extra sprinkles onto the tops before serving.