In a large bowl or stand mixer (no need to clean it out from above, if used) add 2 sticks softened butter and 1⅔ cup sugar. Beat together, scraping down the sides of the bowl as needed until the butter lightens in color, just a few minutes.
Add 2 eggs and 2 tsp vanilla. Beat together.
Add 3½ cups flour, 1 tsp baking soda, 1 tsp salt, 1½ tsp cream of tartar to the bowl. Slowly mix together until just barely combined (don't over-mix).
Remove from stand-mixer and add in cinnamon sugar balls. Use a spoon or spatula to fold in gently until evenly distributed