Directions:

• Heat the oven to 375�F. Line two baking sheets with parchment paper.
• To make the cookies, whisk the shortening into the warm butter in a large bowl until the shortening melts (if there are still a few little solid bits of shortening, don�t worry). Whisk in the brown sugar and vanilla for 30 seconds, and then the egg. Sprinkle the baking soda, salt, cinnamon, and cream of tartar into the bowl, one at a time, vigorously whisking after each. Gently fold in the flour with a flexible spatula just until the last streak disappears. Don�t overmix.
• To make the cinnamon sugar, whisk together the granulated sugar and cinnamon in a small bowl. Scoop 1? 1/2-tablespoon balls of dough with a portion scoop or measuring spoons and drop them in the cinnamon ?sugar, nudging them with your fingers to coat. (No need to roll them into balls first.) Place 9 or 10 on each prepared baking sheet. The dough is super soft. Don�t worry. Bake for 6 to 8 minutes, until the cookies are cracked and slightly domed (they may or may not collapse as they cool�?depends on the temp in your kitchen). Remove from the oven and if too domed/puffy for your liking, immediately press with a spatula to flatten. Enjoy warm or at room temperature. Keep the snickerdoodles in an airtight container on the counter for up to 3 days.