Meanwhile, whisk flour and chicken broth until blended. Cook leeks, pancetta and garlic in large deep skillet on medium heat 8 min. or until white parts of leeks are crisp-tender, stirring frequently. Add cream cheese product and chicken broth mixture; mix well. Cook 2 to 4 min. or until cream cheese is completely melted and sauce is thickened, stirring constantly. Add 3/4 cup shredded cheese; cook and stir 2 to 3 min. or until melted.