In a small microwave-safe bowl, combine chopped cranberries and Grand Marnier, tossing to coat.
Microwave on high for 1 minute, stir, and microwave an additional 30 seconds. Set aside.
In a large mixing bowl, beat the butter, oil, and sugars until combined.
Beat in eggs, vanilla, and orange zest.
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. Do not overmix.
Drain cranberries of any remaining liqueur, and pat dry.
Beat cranberries into cookie dough until just combined.
Line baking sheets with parchment paper or silicone baking mats.
Drop dough by teaspoonfuls onto baking sheets.
Bake at 375 for 8-11 minutes, or until edges and bottoms are lightly browned.
Remove to wire racks to cool completely.