Toast the pine nuts in a 350 degree oven for 6 to 7 minutes, or until golden brown. Cool. Caution: pine nuts burn easily. Preheat the oven to 375 degrees and fire up an outdoor grill. Peel onions and cut them in half, top to bottom. Brush onions with oil and place cut side down on the preheated grill. Barbecue until grill marks form. Place on a cookie sheet and finish cooking in the oven until tender, about 25 minutes.
Meanwhile, make the pine nut butter. Place the 1/2 cup pine nuts in the bowl of a food processor and pulse several times until finely ground. Add butter, lemon zest, rosemary, black pepper and salt. Process until mixture is well blended. Spread the tender onions liberally with pine nut butter. Return to the oven to cook just until butter is melted, about 2 minutes.
Serve onions warm, sprinkled with grated parmesan cheese and additional toasted pine nuts. Garnish plates with lemon wedges and rosemary sprigs.
Serves: 4 as an entree
8 as an appetizer