Line 2 (15x10x1-inch) pans with foil;spray with cooking spray.
Mix first four ingredients until blended; shape into 32 (1-1/2 inch) balls, using 1/4 cup for each.
Place 16 meatballs in each prepared pan. Bake 16 to 18 minute or until done (160 degrees F).
Mix 1 jar (12 oz.) beef gravy, 1/2 cup sour cream and 2 tablespoons chopped fresh parsley in large skillet; cook on medium-low heat 3 minute or until heated through, stirring occasionally. Add 16 hot meatballs; stir to evenly coat.
How to freeze meatballs: Loosely pack cooled meatballs in freezer-weight resealable plastic bags. Lay bags flat in freezer so meatballs freeze individually. Store up to 3 months. Thaw in refrigerator several hours or overnight before using as desired.