Step 1

In a medium bowl, whisk together the flour, cream of tartar, baking soda, cinnamon and salt.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, beat the coconut oil and sugar on medium for 2 minutes, until sort of fluffy (it won’t look quite the same as with regular butter).

Step 3

Add in the egg, egg yolk and vanilla and beat again for about 30 seconds, until well combined.

Step 4

With the mixer on low, add in the flour mixture and mix until combined.

Step 5

Transfer the bowl to the refrigerator and chill for 30 minutes.

Step 6

Meanwhile, preheat the oven to 350ºF. Line a large baking sheet with parchment paper.

Step 7

In a small bowl, mix together the sugar and cinnamon for rolling.

Step 8

Scoop about 1 ½ to 2 tablespoons of the chilled dough and form into balls (about 1 ½ inches in size). Roll / press the balls in the sugar mixture and place on the prepared baking sheet about 2 to 3 inches apart.*

Step 9

Bake for about 10 to 11 minutes, until the cookies are just set (they’ll look a little underdone in the centers but that’s okay - don’t overbake!). Let the cookies cool for about 10 minutes, then remove to a wire rack.