Preheat oven to 350 degrees. In a mixing bowl whisk together flour, cream of tartar, baking soda, cinnamon, nutmeg and salt for 20 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment, blend together butter, shortening, granulated sugar, and brown sugar until creamy. Mix in eggs then mix in vanilla and rum extract. With mixer set on low speed slowly add in flour mixture and mix just until combined.
Scoop dough out 1 1/2 Tbsp at a time and shape into balls.
In a small bowl whisk together 1/4 cup granulated sugar, nutmeg and cinnamon and roll dough balls into mixture to evenly coat. Place 2-inches apart Silpat or parchment paper lined baking sheets. Bake in preheated oven 9 - 10 minutes (they should appear slightly under-baked). Cool on baking sheet several minutes then transfer to a wire rack to cool completely. Store in an airtight container.