Preheat the oven to 400℉. Line two baking sheets with parchment paper, or lightly coat them with nonstick cooking spray.
In a medium bowl, add 3 ¼ cup all-purpose flour - leveled in the measuring cups, 1 ½ tsp cream of tartar, 1 tsp baking soda, and ½ tsp salt. Mix and set aside for now.
In a separate large bowl, cream 1 cup unsalted butter - softened to room temperature, using a hand mixer until smooth.
Add 1 ⅓ cup granulated sugar and ⅓ cup packed brown sugar to the creamed butter. Mix again with a hand mixer for roughly 2 minutes until it's smooth and creamy, scrape down the sides of the bowl with a spatula when needed.
Add 2 large room-temperature eggs and 1 ½ tsp vanilla extract to the creamed butter and sugar, and beat until smooth.
Add half of the flour mixture and beat until just combined. Add in the other half of the flour mixture and repeat.
You may need to stir the cookie dough by hand to mix in the rest of the flour. Stir gently and do not over-mix - just enough that all the ingredients are combined.
In a shallow bowl or plate, mix ⅓ cup granulated sugar and 1 ½ Tbsp cinnamon for the cinnamon sugar coating.
Create a ball by rolling 1 Tbsp of cookie dough in the palms of your hands. Roll the ball in the cinnamon sugar mixture until it's evenly coated.
Place the cookie dough balls 2" apart on two baking sheets. Bake for 6-8 minutes, remove from the oven, and let sit for 2 minutes on the baking sheet. Use a spatula to gently scoop under the cookie and transfer to a rack to cool completely.
Recipe Notes:
Use room-temperature butter and eggs - these combine easier leading to a smoother dough.
Cream the butter and sugar until it's light and fluffy. This process forces air into the dough, helping the cookies rise to give them a lighter texture.
Chilling the dough balls helps to solidify the butter with other ingredients leading to soft and chewy cookies that won't spread out in the baking sheet.
Do not overbake your cookies, you want them slightly underbaked in the center keeping them soft and chewy.
Store the cookies in an airtight container or ziploc bag at room temperature. If you live in a more humid climate, then try storing these in the fridge to prevent them from getting mushy.
Use a sheet of parchment paper in between stacked cookies to prevent them from sticking to one another.
Freezing cookies - These cookies store great in the freezer! Add to a freezer bag, and remove as much air as possible as this can cause freezer burn. You can store up to 6 months. When ready, let them thaw at room temperature or eat them frozen. We freeze our cookies all the time and eat them straight from frozen.