Cut pears in half and remove the seeds.
Marinate pears overnight, or for at least 4 hours in Grand Marinier, brown sugar and vanilla, in a sealable plastic bag.
Preheat a grill for high heat. When the grill is hot, lightly oil the grate.
Drain pears and place on hot grill just long enough to get grill marks on both sides, approximately 2 minutes per side.
While pears are grilling, mix mascarpone cheese with crushed cookies (your favorite variety and brand), then add the liqueur and stir well. Set aside.
Just before serving, add the mascarpone-cookie mixture to each pear half with a large spoon, filling in the hole where you removed the seeds.
Place back on grill for an additional 2 minutes, rounded side down.
Remove from grill and place on small plates.
Serve with additional cookies or ice cream on the side.
