Spray 4 1/2- to 5-quart slow cooker with cooking spray. Mix mushrooms onions melted butter soy sauce salt and pepper in cooker. Pour vegetable broth over vegetable mixture.
Cover; cook on Low heat setting 7 to 8 hours or until vegetables are very tender and browned.
Stir in tortellini and cream cheese. Cover; cook on Low heat setting 15 minutes. Cook and stir 14 to 16 minutes longer or until tortellini are tender. Stir in spinach. Let stand 5 minutes. Top with Parmesan cheese and basil.,