In a large saucepan over medium-high , saute the onions in the butter until soft. Add the squash and the apples and continue to saute for an additional 3 minutes.
Add the chile and broth to the onion mixture and bring to a boil over high heat. Reduce the heat, cover partially and simmer until the squash and apples are very tender, about 30 to 45 minutes.
Add the lemon peel, chicken (if using), pepper, and applejack. Season with salt to taste and simmer for an additional 10 minutes. Add the vinegar if the soup is too sweet.
Serve the soup in large bowls garnished with the croutons.
For the Croutons
Preheat the oven to 325 degrees.
Spread the bread cubes on a baking sheet and let them dry out at room temperature for a couple of hours.
In a skillet, heat the olive oil and margarine. Add the garlic and saute until the garlic just starts to brown, being careful not to let them burn. Remove the garlic and discard. Add the chile and the cumin and toss the crumbs in the mixture until well coated.
Spread the bread cubes on the baking sheet and bake for 10 minutes or until lightly browned. Allow the cubes to cool at room temperature.