Preheat the oven to 375°F.  Line 2 baking sheets with parchment paper.  

Whisk together the flour, cream of tartar, baking powder and salt in a medium bowl.  Set aside.

In a large mixing bowl, cream together the vegetable shortening, softened butter granulated sugar until light and fluffy for about 2-3  minutes.

 Beat in the eggs, one at a time, until well incorporated, followed by the vanilla extract. Scrape down the sides of the bowl as needed. 

Gradually add the flour mixture into the butter/sugar bowl.  mixing until just combined. Be careful not to overmix; the dough should come together without any dry streaks. Optional: Chill the cookie dough for at least 30 minutes before doing the next step. 

In a small bowl, stir together the cinnamon and sugar mixture. 

Using a tablespoon or cookie scoop, scoop evenly sized cookies and roll each cookie in the cinnamon sugar.  

Place each cookie on the baking sheet with about 2 inches of space to allow for spreading in the oven. 

Bake the cookies for 8-10 minutes, until the cookies are golden brown on the edges.