1. Bring to simmering juice, sugar, grenadine, cinnamon and allspice in saucepan. Add pears; poach for 35 to 40 minutes or until tender. Remove with slotted spoon to bowl.
2. Boil liquid 10 minutes to reduce to 1 cup. Whisk in dissolved cornstarch; cook, whisking, until thickened. Cover and reserve sauce.
3. Heat oven to 400 degrees F. Coat baking sheet with cooking spray. Unfold pastry; roll to 11-inch square. Cut out four 5-inch hearts. Place on prepared sheet. Cut scraps, into Xs, Os and hearts.
4. Bake large hearts in 400 degree F oven 12 minutes, cutouts 6 minutes, until golden. Cut out centers of hearts, without going through bottom, leaving 3/4-inch sides.
5. Grind nuts and sugar in processor. Add butter and liqueur. Whirl until paste. Spread in centers of heart.
6. Cut pear halves in half lengthwise. Cut each quarter lengthwise into thin slices, leaving attached at stem end. Fan out pears; arrange 2 quarters on each tart as pictured. Spoon reserved sauce on serving plates. Place hearts in center; surround with cutouts. Garnish with mint. Makes 8 servings (half tart).