Whisk Dry Ingredients: In a medium bowl, stir together the flour, cream of tartar, baking soda, and salt. Set aside.
Cream Butter & Sugar: In a large mixing bowl, cream the softened butter (or Crisco) and 1 1/2 cups of sugar together until light and fluffy (about 2-3 minutes).
Add Wet Ingredients: Beat in the eggs one at a time, followed by the vanilla extract, scraping down the sides of the bowl to ensure everything is incorporated.
Combine: Gradually add the dry flour mixture to the wet ingredients. Mix just until combined and no streaks of flour remain.
Chill the Dough: Cover the bowl with plastic wrap and refrigerate for 20–30 minutes. (This step is crucial to prevent the cookies from spreading too much!)
Preheat & Prep: Preheat your oven to 350°F (175°C). In a small shallow bowl, mix the 1/4 cup sugar and cinnamon together.
Roll: Scoop the chilled dough and roll into small balls (about 1 inch). Drop them into the cinnamon-sugar mixture and roll until heavily coated.
Bake: Place dough balls on a baking sheet (lined with parchment or a "broken in" ungreased pan). Bake for 8–9 minutes. They should look puffed and slightly crackly on top but still soft.
Cool: Let them cool on the baking sheet for 2 minutes before transferring to a wire rack.