In a bowl of an electric stand mixer (fitted w/ a paddle attachment), cream together the softened butter on medium-high speed, for about 1 minute or so.
Add the pure cane sugar and continue beating on medium-high speed until fluffy.
Add in the egg and vanilla extract and reduce the speed to medium, ensuring that everything is well combined. Scrape down the sides as needed.
In a separate bowl, whisk together the all-purpose flour, baking powder, sea salt, baking soda, and cream of tartar.
Reducing the mixer's speed to low, slowly add the dry ingredients to the butter-sugar mixture and continue mixing until well incorporated.
Once combined, fold in the sprinkles, using a rubber spatula.
Cover the dough in the bowl and refrigerate for 1-2 hours.
Once chilled, remove from the refrigerator and let it sit at room temperature for a few minutes if it has hardened a lot.
Preheat oven to 350 degrees Fahrenheit and line a baking sheet with parchment paper.
If manageable, using an ice cream scoop, scoop a large amount of the dough and roll into a ball (about 3-4 Tbsps). Place on baking sheet and repeat. **NOTE: You may only fit about 3 at a time to ensure that they don't touch each other during baking.**
Place oven rack to the center and bake for 10 minutes. **NOTE: Be sure to place unused cookie dough back in the refrigerator to chill until ready to use again.**
At the 10 minute mark (cookies should be slightly puffed in the center), lift baking sheet and let it drop against the rack. Repeat about twice if needed. This allows the edges to set and the inside to fall down. **Do this process for both baking sheets.** Then 3 minutes later, repeat the process again, doing so another time after 3 minutes again. **NOTE: You should bang baking sheets a total of 3 x’s for baking session.**
Remove the oven and let them cool for 4-5 minutes before transferring them to a cooling rack to cool completely.
Once cooled, cookies will become more hardened, but still soft enough to enjoy!
Repeat steps until all of the batter is baked into cookies.
Bon Appetit!