HEAT oven to 425ºF.
BROWN meat in large skillet; drain. Return meat to skillet; stir in 3/4 cup water. Add Vegetables and Seasoning Mix; stir. Bring to boil; cook 1 min. Simmer on medium-low heat 5 min., stirring frequently. Stir in tomatoes. Spoon into 2-qt. casserole sprayed with cooking spray; cover with Cheese Sauce.
ADD remaining water to Cornbread Mix; stir until blended. Spread over cheese sauce.
BAKE 17 to 19 min. or until filling is heated through and topping is golden brown.