Combine first 4 ingredients on a foil-lined jelly-roll pan. Bake at 400° for 30 minutes or until squash is tender. Set aside.
Sauté next 3 ingredients in bacon drippings in a large skillet until tender. Stir in curry powder; toast 30 seconds. Add calabaza, curry paste, thyme, and bay leaf; stir to combine. Add stock and cream; bring to a boil. Cover, reduce heat, and simmer 30 minutes.
Puree mixture in a blender, pour through a wire-mesh strainer, and press with the back of a spoon. Season with salt and white pepper to taste. Garnish, if desired.