Cream together butter, shortening, and 1 1/2 cups sugar. Add eggs and vanilla and mix well.
Add the flour, cream of tartar, baking soda and salt and stir until combined.
Shape dough by spoonfuls into balls. I grease my hands with cooking spray since the dough is slightly sticky. I also like to put one finished tray of rolled cookies in the fridge while I"m rolling the second. Then when you're ready to roll them in cinnamon and sugar they are easier to handle.
In a separate bowl, mix the 4 tablespoons granulated sugar and the cinnamon. Roll balls of dough in mixture. Place dough about 2 inches apart on a parchment lined baking sheet.
Bake 8 to 9 minutes (don't over bake!) Remove immediately (and carefully, with a good spatula!) from baking sheets onto a cooling rack to cool completely.
Storing and Freezing Instructions:Store in an airtight container at room temperature for 2-3 days. To freeze the cookie dough, form dough balls and roll them in cinnamon sugar. Place cookie dough balls in a freezer safe bag in the freezer for up to 3 months. Bake from frozen for 2 to 3 minutes longer than recipe states.To freeze baked cookies, allow them to cool completely and place them in an air-tight freezer safe container for 2-3 months.