Preheat oven to 375°F. Line two baking sheets with Silpat mats and spray with cooking spray.
Combine flour, baking soda, and cream of tartar in a medium bowl, stirring with a whisk.
Combine 1 cup of sugar and butter in a large bowl; beat with a mixer at medium speed until well blended. Add the agave, vanilla and egg; beat well. Gradually add the flour mixture to the sugar mixture, beating just until combined. Cover and chill for 10 minutes.
In a medium bowl, combine 3 tbsp sugar with pumpkin pie spice, stirring with a whisk to combine. With wet hands (you can keep a cup of water close), shape dough into 42 (1-inch) balls. Roll balls in sugar/pumpkin pie spice mixture.
Place balls 2 inches apart onto baking sheets and slightly flatten with a fork.
Bake 375°F for 5-7 minutes (cookies will be slightly soft). Cool on baking sheets for 2 minutes. Remove from pans; cool completely on wire racks. Enjoy!
Notes
*There was a little extra sugar leftover, so I deducted from the n.i..