Preheat the oven to 400°F. Line baking sheets with parchment.

In a small bowl, mix together the flour, cream of tartar, baking soda, and salt.

In a medium bowl, beat the butter, shortening, and 1 ½ cups sugar with a handheld mixer, or a standing mixer if you have one, until light and fluffy, for about 2 minutes. Add eggs, and beat to combine. Add dry ingredients, and beat to combine.

In a small bowl, combine remaining ¼ cup sugar and the spices. Shape balls out of the dough–you want them to be about 1 ½ inches in diameter. Roll all the balls through the spice-sugar mixture. Place about 2 inches apart on the prepared baking sheets. Bake until the cookies are set in center and begin to crack (they will not brown), about 8 minutes, rotating the baking sheets after 4 minutes. Let the cookies cool on the sheets for a few minutes before transferring to a rack to cool completely.