In a large mixing bowl, beat the butter, oil, and sugars until combined.
Beat in eggs and extracts.
In a large bowl, whisk together flour, baking soda, and cream of tartar.
Gradually add flour mixture to the butter mixture, beating until just combined after each addition. Do not overmix.
Line baking sheets with parchment paper or silicone baking mats.
Drop dough by teaspoonfuls onto baking sheets, about two inches apart.
Flatten with a glass dipped in sugar. Sprinkle a little extra on top, if you'd like!
Bake at 350 for 12-15 minutes, or until edges and bottoms are golden brown.
Remove to wire racks to cool.