Prick squash several times with fork to allow steam to escape. Place in oven and microwave at High (100%) until soft when tested with fork, 10 to 12 minutes. (If oven doesn't have carousel, rotate and turn squash after half the cooking time. Let stand 5 minutes. Cut in half and remove seeds.
Place cut side up in 10" square casserole.
Combine cranberry sauce, honey and allspice in small bowl. Microwave at High (100%) until hot and bubbly, 3 to 4 minutes, stirring after half cooking time. Spoon into squash halves. Microwave at High (100%) 2 to 3 minutes until heated through.