Preheat your oven to 350°F (175°C).

In a mixing bowl, beat the softened butter and granulated sugar together until light and fluffy.

Add in the egg and vanilla extract, mixing until fully combined.

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

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Gently fold in the rainbow sprinkles.

Using a cookie scoop or spoon, drop rounded tablespoons of dough onto a baking sheet lined with parchment paper, leaving space between each cookie.

Bake in the preheated oven for 8-10 minutes or until the edges are lightly golden.