Preheat oven to 375°F. Line baking sheets with parchment paper.
In a small bowl, whisk together flour, baking soda, baking powder and salt. Set aside.
In a large bowl, cream together the butter and sugar until light and fluffy. Add in egg and vanilla and mix until combined. Scrape the sides of the bowl down.
Gradually add in the dry ingredients and mix until just combined. If using, mix in the nonpareil sprinkles.
Use a small cookie scoop to create dough balls about 2 teaspoons each. Gently roll each scoop of dough into a ball and place onto prepared cookie sheets, leaving about 2 inches of space between each cookie.
Bake in preheated oven for 8 minutes. Allow cookies to cool on the baking sheets for a couple of minutes before moving them to a wire rack to cool completely.
If desired, top or sandwich cookies with buttercream frosting.
Notes
*If using the vanilla buttercream linked above, I recommend cutting it in half.