Drain tomatoes, reserving liquid. Add enough water to reserved liquid to measure 1-3/4 cups. Cook chicken in large skillet sprayed with cooking spray on medium-high heat 5 min. or until done, stirring occasionally. Add Shell Macaroni, tomatoes and tomato liquid; stir. Bring to boil; cover. Simmer on medium-low heat 9 to 10 min. or until macaroni is tender. Remove from heat. Stir in Cheese Sauce and sour cream until well blended. Top with shredded cheese; let stand, covered, 1 to 2 min. or until melted. Substitute: Prepare using KRAFT 2% Milk Shredded Sharp Cheddar Cheese. Size-Wise: Enjoy your favorite foods while keeping portion size in mind. Variation: Prepare as directed, substituting 1 cup TACO BELL® HOME ORIGINALS® Thick 'N Chunky Salsa and 1-1/2 cups water for the chunky tomatoes and tomato liquid mixture, and reducing the sour cream to 1/4 cup. Nutrition Information Per Serving (shredded sharp cheddar cheese): 530 calories, 22g total fat, 10g saturated fat, 115mg cholesterol, 1180mg sodium, 41g carbohydrate, 2g dietary fiber, 7g sugars, 38g protein, 15%DV vitamin A, 6%DV vitamin C, 30%DV calcium, 15%DV iron. Nutrition Information Per Serving (2% Milk shredded sharp): 510 calories, 20g total fat, 9g saturated fat, 5g trans fat, 115mg cholesterol, 1200mg sodium, 41g carbohydrate, 2g dietary fiber, 6g sugars, 39g protein, 15%DV vitamin A, 6%DV vitamin C, 40%DV calcium, 15%DV iron. TACO BELL® and HOME ORIGINALS® are trademarks owned and licensed by Taco Bell Corp.