Preheat the oven to 350 degrees Fahrenheit. Line a cookie sheet or two with parchment paper, or a silicone liner, and set it aside.
Add your butter and sugar to a large mixing bowl and beat them together for about 2 minutes until the mixture is creamy, and light in color.
Add in the egg and vanilla extract and stir them into the butter mixture until combined.
Add in the flour, baking powder, baking soda, and salt. Stir it all together until you have a nice soft dough, scrape the bottom of the bowl as needed while mixing.
Add in the sprinkles and carefully stir them into the cookie dough.
Scoop the dough by the 1.5 to 2 TBS and roll them into balls. (You can dip the tops of the cookie balls into more sprinkles if you want them to have more). Place the balls a couple inches apart on the prepared baking sheet.
Bake the cookies for 7 to 9 minutes, or until the edges just start to turn golden. The middle may not look done yet.
Remove the pan from the oven and leave the cookies on the sheet for about 10 minutes.
Transfer them to a cooling rack to cool completely, or enjoy warm.