In a medium sized bowl combine the flour, baking soda, salt, and cream of tartar. Stir to combine.
In a separate large bowl combine the confectioners’ sugar, brown sugar, and granulated sugar. Whisk to combine.
Into the sugar mixture add the softened butter, eggs and vanilla. Using a hand mixer beat on medium/high speed until smooth.
Using a wooden spoon, fold in the dry ingredients until combined. Add in the sprinkles and chocolate chips, fold until incorporated.
Using a cookie scoop, portion cookies onto a cookie sheet.
Bake cookies for 10-12 minutes (see notes), until cookies are slightly golden around the edges.
Transfer cookies to cooling racks and store in an airtight container at room temperature for up to 5 days.
Notes
* If using margarine instead of butter decrease baking time to 10 minutes maximum, but check cookies at 8 minutes. The cookies will also spread more using margarine. ** There are many different types of sprinkles, I prefer to use jimmys in this recipe but quins will work too. Do not use nonpareils. (See blog post for more information on the types of sprinkles)
The cookie dough can be frozen before it is baked, to make fresh cookies on demand! To freeze cookie dough: portion out cookie dough on a baking sheet and freeze until solid, at least 6 hours. Transfer frozen cookie dough to a zip top bag and store in the freezer until ready to bake.
Baking frozen cookie dough: Preheat oven to 350°F and bake from frozen for 15-17 minutes.