Preheat oven to 350° F.
In a large bowl, combine the butter, shortening, 1-1/2 cups sugar and the eggs and mix thoroughly with an electric mixer on medium speed until creamy and well combined, 1 to 2 minutes. Sift together the flour, cream of tartar, baking soda and salt, and mix into the butter mixture.
In a small bowl, mix together the remaining 2 tablespoon sugar with the cinnamon.
Shape dough into 1-1/2 balls (about 1 tablespoon per ball), and roll each ball in the cinnamon-sugar. Arrange the dough balls 2 inches apart on engrossed cookie sheets. Bake 10-12 minutes, checking after 10. We like the cookies golden brown on the edges and soft in the middle.
Cream Cheese Spread
Beat cream cheese. sugar and vanilla until smooth.