Preheat oven to 400°.
To prepare soup, cut squash in half lengthwise. Discard seeds and membrane. Place squash, cut-sides up, on a foil-lined baking sheet. Drizzle with honey; sprinkle with 1/4 teaspoon salt and 1/4 teaspoon pepper. Bake at 400° for 1 hour or until tender; cool. Scoop out squash with a spoon; discard skin.
Heat 1 teaspoon oil in a saucepan over medium-high heat. Add onion, carrot, celery, and garlic; sauté 10 minutes or until tender. Remove 3/4 cup vegetables; set aside. Add broth to pan; cook over medium heat 12 minutes. Stir in squash. Reduce heat; simmer 15 minutes. Place soup in food processor; process until smooth. Add 1 cup milk, 1/2 teaspoon salt, and dash of pepper; set aside.
To prepare croquettes, combine reserved vegetables, turkey, 1/4 cup breadcrumbs and next 6 ingredients (1/4 cup breadcrumbs through egg white). Cover and refrigerate 30 minutes or until firm. Shape into 12 (1-inch-thick) patties; press 1 1/2 cups breadcrumbs onto patties.
Heat 3 3/4 teaspoons oil in a nonstick skillet over medium heat. Add 6 patties to pan; cook 3 minutes on each side or until golden brown. Remove croquettes from pan; keep warm. Repeat procedure with remaining oil and patties.
Reheat soup. Divide evenly among 6 bowls; top with croquettes. Garnish with fresh sage leaves, if desired.