Microwave milk with 1 Chicken flavored Bouillon Cube in small microwave-safe bowl at HIGH 20 seconds; stir until dissolved. Combine ground turkey, onion, milk mixture, bread crumbs and eggs in large bowl; shape into 75 (1-1/2 inch) meatballs.
Melt 2 tablespoons butter in 12-inch nonstick skillet over medium heat and brown 25 meatballs, turning gently, about 4 minutes; add to slow cooker. Melt 1 tablespoon Spread and brown 25 meatballs; add to slow cooker. Repeat with remaining 1 tablespoon Spread and meatballs.
Spray 6-quart slow cooker with nonstick cooking spray; set aside.
Add water, cranberry sauce and remaining Bouillon Cube to slow cooker. Cook covered on HIGH 3 hours or until meatballs are done.
Combine sour cream with flour with wire whisk. Whisk 1/2 cup liquid from slow cooker into sour cream mixture. Gently stir back into slow cooker; combine well. Cook covered an additional 30 minutes or until thickened. Stir in parsley just before serving.