Spicy Chicken with Grilled Pineapple

8 scallions (chopped) plus 1/4 cup dark-green 2" long thin strips for garnish
1 medium onion (chopped)
3 garlic cloves (pressed)
3 Tbsp cider vinegar
2 Tbsp soy sauce
2 Tbsp vegetable oil (plus additional for grill)
1 jalapeno chile (chopped) (optional)
1 1/2 Tbsp fresh thyme leaves
1 Tbsp packed light brown sugar
2 tsp allspice
1/2 tsp freshly ground nutmeg
1/2 tsp cinnamon
3 1/2 lbs chicken (your choice of breasts, thighs, or drumsticks)
1 fresh pineapple (about 4 lbs)
2 1/2 Tbsp packed light brown sugar

Make a marinade:  Place first 12 ingredients, except scallion garnish, in a food processor or blender and puree until almost smooth.  Transfer half of puree to a small bowl and keep chilled, covered, for sauce.

Place remaining puree in a large heavy-duty resealable plastic bag with chicken and seal, turning to coat well.  Marinate, chilled, turning bag occasionally, at least 8 hours or overnight, placing bag in a large bowl to catch any leaks.

Preheat grill and lightly oil rack.  Let chicken stand in marinade at room temp for 30 minutes before grilling.  Meanwhile, cut sides and ends off pineapple.  Cut crosswise into 15 slices about 1/4" thick.  Sprinkle one side of each slice with 1/2 tsp packed light brown sugar.  Place sugared side down on rack and grill, turning once, until golden brown, about 3 minutes.  Transfer to a platter, alternating slices with scallion garnish.

Remove chicken from marinade (discard marinade) and grill over moderate heat, turning occasionally, until cooked through, 35 - 45 minutes, depending on size.  Transfer to platter with pineapple and serve with remaining sauce on side (exercise caution; sauce is spicy if you include the chile pepper).