Place all ingredients in a 7-qt. slow cooker (excluding croutons & chopped basil). Turn to High for 5 hours.
After 5 hours, remove the thyme, fresh basil and parmesan rind.
Place half to most of the liquid into a blender (amount depends on desired smoothness); blend on high speed.
Return to slow cooker and stir in blended soup, turning to Low heat. Add the cream and salt and pepper to taste.
To prepare croutons, add croutons to a baking sheet and evenly coat with cooking spray. Sprinkle croutons with shredded parmesan cheese.
Bake for 5 - 10 minutes or until croutons are browned and cheese is melted.
Serve soup while hot with parmesan croutons and freshly chopped basil.