Spray 3 1/2- to 4-quart slow cooker with cooking spray. In cooker, mix all ingredients except mixed vegetables, spaghetti, beans and pesto.
Cover; cook on Low heat setting 7 to 9 hours.
Stir in mixed vegetables, spaghetti and beans. Increase heat setting to High. Cover; cook 20 minutes longer. Garnish each serving with about 1 1/2 teaspoons pesto.