Preheat your oven to 375°F and line a baking sheet with either parchment paper or a silicone baking mat. This will prevent the cookies from sticking and make cleanup easier. Set the tray aside for now.

In a small mixing bowl, combine the flour, baking soda, cream of tartar, and 1/2 teaspoon of cinnamon. Use a fork to gently mix the ingredients until they’re evenly combined. This is your “dry” mixture. Set this aside as well.

In a large mixing bowl (or a stand mixer, if you have one), add the softened butter and 3/4 cup granulated sugar. Beat on medium speed for about 2 minutes until the mixture looks light and fluffy. This step is called "creaming" and helps give your cookies a nice texture.

Scrape down the sides of the bowl using a spatula to make sure everything is mixed evenly. Now, add the egg and vanilla extract. Mix on low speed just until everything is combined—be careful not to overmix.

Gradually add your dry ingredients to the butter and sugar mixture, stirring on low speed until a cookie dough forms. If you don’t have a mixer, you can mix by hand—just be patient and stir until the dough comes together.

In a small bowl, mix together the remaining 2 tablespoons of sugar with 2 teaspoons of cinnamon. This will be your cinnamon-sugar coating.

Scoop about 2 tablespoons of dough (about the size of a golf ball) and roll it into a ball. Roll each dough ball in the cinnamon-sugar mixture until it’s fully coated.

Place the dough balls on the prepared baking sheet, leaving about 2 inches of space between each cookie so they have room to spread as they bake.

Bake the cookies for 10-11 minutes. You’ll know they’re done when the edges are slightly curled and the cookies look puffed up, even if the centers seem a little soft (they’ll firm up as they cool).

Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack (or a plate). Now, enjoy your homemade snickerdoodles!