In a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, cream the butter and both sugars together on medium speed for 2 minutes.
1 cup Butter, ½ cup Brown Sugar, 1 cup Granulated Sugar
Scrape down the sides of the bowl. Add the egg, egg yolk and vanilla extract. Beat again on medium speed for 1 minute. Add the peanut butter and mix.
1 Large Egg, 1 Large Egg Yolk, 2 teaspoons vanilla extract, ½ cup Smooth Peanut Butter
Pour the dry ingredients in and beat on low speed until just combined.
Whisk the cinnamon and sugar together in a small bowl.
1 tablespoons Ground Cinnamon, ¼ cup Granulated Sugar
Use a cookie scoop or spoon to scoop out 3 tablespoons of dough and roll into balls. You should have about 16 cookies. Roll each cookie dough ball into the cinnamon sugar mixture. You'll have a little bit of cinnamon sugar leftover.
Place the cookie dough balls on the prepared baking sheets, a few inches apart. I put about 8 cookie dough balls per tray. For any cookie dough that isn't being baked right away, place in the fridge.
Bake the cookies for 8-10 minutes. The cookies will have slightly puffed up and cracked.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way.
Cream of Tartar: what makes snickerdoodles different from regular sugar cookies is the cream of tartar, so there isn't anything you can replace it with.
Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. I'm using Diamond Crystal Kosher Salt and not Morton Kosher Salt, which is far too salty for this recipe!Storage: keep the baked cookies in a tupperware for up to 1 week at room temperature. Freeze baked cookies in an airtight container in the freezer for up to 2 months. Let thaw before enjoying.