Preheat the oven to 400 degrees. Line a large baking sheet (you may need two) with foil. Place the squash, onion, bell pepper, and bacon slices on the baking sheet(s) in a single layer. Season generously with salt and pepper. Roast the vegetables in the oven for 25-30 minutes, stirring the pans halfway through cooking, until the squash is tender enough to puree.
*While the vegetables are roasting, cook the other four slices of bacon on the stovetop. Drain and crumble. Set aside.
To a dutch oven, add the roasted vegetables and bacon. Pour in 2 cups of the chicken stock. Using an immersion blender, blend the soup until mostly smooth (texture will be thick and slightly chunky), adding more chicken stock as needed. Turn the burner onto to medium heat, and heat the soup through until it just begins to steam and simmer. Ladle the soup into bowls, then top with crumbled bacon, goat cheese, and green onions or chives.