Spray 4- to 5-quart slow cooker with cooking spray. If pork roast comes in netting or is tied, remove netting or strings. Place pork in cooker. In small bowl, mix syrup, garlic, sage, bouillon granules and 1/2 cup water; spoon over pork. Arrange squash, carrots and onions around pork.
Cover; cook on Low heat setting 8 to 9 hours.
Remove pork and vegetables from cooker; cover to keep warm. If desired, skim fat from juices in cooker. Pour juices into 4-cup microwavable measuring cup. In small bowl, mix cornstarch and 1/2 cup water until smooth; stir into juices in cup. Microwave uncovered on High 2 to 3 minutes, stirring every minute, until mixture thickens. Serve with pork and vegetables.