1. Preheat oven to 350 degrees.
2. In a large mixing bowl, cream butter and sugar for 4-5 minutes until light and fluffy. Scrape the sides of the bowl and add the eggs and vanilla. Cream for 1-2 minutes longer.
3. Stir in flour, cream of tartar, baking soda, and salt, just until combined.
4. If time allows, wrap the dough and let refrigerate for 20-30 minutes.
5. In a small bowl, stir together sugar and cinnamon.
6. Roll dough into small balls until round and smooth. Drop into the cinnamon-sugar mixture and coat well. Using a spoon, coat for a second time, ensuring the cookie balls are completely covered.
7. Place on a parchment paper-lined baking sheet. Bake for 9-11 minutes. Let cool for several minutes on baking sheet before removing from the pan.
1. To ensure the cookies don't puff up too much and keep their shape, make sure that the cookies are chilled before placing in the oven. I line my baking sheet with my coated cookies, place them in the fridge, and then work on my second batch of coating the cookies while the first batch chills in the fridge. By the time I'm done coating the second batch, I take the first batch out of the fridge and place them in the oven, then put the second batch in the refrigerator and let them chill as the first batch bakes. Do this for however many batches you're making!
2. To make flatter snickerdoodles, press down in the center of the ball before placing in the oven. This helps to keep them from puffing up in the middle.