In bowl of a stand mixer, combine butter, sugars and 1/4 cup of Cinnadust™. Beat at medium-high speed, about 4 minutes. Add the egg, egg yolk and vanilla extract. Beat on medium speed until combined.
In a small bowl, combine flour, cream of tartar, baking soda, and cinnamon. With mixer running at low speed, add flour mixture to butter mixture. Mix until just combined.
Measure dough into 2 tablespoon sized pieces. Roll into balls, then roll balls in remaining 1/4 cup Cinndust™ to coat. Place 3″ apart on two parchment lined sheet trays. Flatten each ball until 3/4″ thick.
Bake cookies for 10 minutes. Let cool on tray for 5 minutes, then cool completely on rack.
