Heat oven to 400 degrees F. Grease a 15 1/2 x 10 1/2 x 1-inch jelly-roll pan. Cut 3 acorn squash lengthwise, seed, then brush cut surfaces and inside with 1 tablespoon maple syrup. Arrange squash, cut-side down, on pan. Bake in 400 degrees F. oven for 30 to 40 minutes, until tender.
Meanwhile, toast 1/2 cup walnuts, chopped, in nonstick skillet over medium heat, stirring, 5 minutes or until golden.
Transfer to paper towel. Heat 2 teaspoons canola oil in same skillet over medium-high heat. Add 1 finely chopped large onion, and 1 thinly sliced large stalk of celery; sauté 3 minutes, until just tender. Add 1 Granny Smith apple, cut into 1/4-inch cubes; 1/3 cup golden raisins, chopped; 1/4 cup uncooked bulgur wheat; 3/4 cup fat-free, reduced-sodium chicken broth; 1/4 teaspoon ground cinnamon; and 1/4 teaspoon salt
Cover; simmer 15 minutes, until bulgur is tender and liquid absorbed. Stir in toasted walnuts. Reduce oven to 375 degrees F. Flip squash cut-side up. Fill with apple mixture. Drizzle with 1 tablespoon syrup. Bake in 375 degrees F. oven for 15 minutes.