Preheat oven to 350°.
Heat oil in a medium saucepan over medium-high heat. Add onion, wheat berries, and mustard seeds; sauté 3 minutes or until onion is tender. Add nuts, ginger, and jalapeño; sauté 1 minute. Add water, salt, and broth; bring to a boil. Cover, reduce heat, and simmer 2 hours or until tender. Stir in minced cilantro and juice. Remove from heat; keep warm.
While wheat mixture cooks, prepare squash. Cut squash lengthwise in half; discard seeds. Combine syrup and cinnamon; brush over squash. Place squash halves, cut sides down, on a baking sheet coated with cooking spray. Bake at 350° for 40 minutes or until tender. Divide the wheat mixture evenly among squash halves. Garnish with cilantro sprigs, if desired.