Peel carrots, apple and onion; cut all into 1/2-inch cubes and place in slow cooker. Stir in butternut squash and vegetable broth; cook on HIGH for 3 hours (or low for 5 hours) or until vegetables are soft.
Puree the vegetable mixture using a stick blender (or cool slightly and puree in batches in electric blender and return to slow cooker)
Stir in Alfredo sauce, syrup, salt, and pumpkin pie spice. Ladle soup into serving bowls; top with 1 tablespoon each pumpkin seeds and cheese. Serve