Queso Baked Nachos

Preheat oven to 350°. In a large skillet, cook and crumble beef over medium heat until no longer pink, 5-7 minutes; drain. Stir in taco seasoning and water; bring to a boil. Reduce heat; simmer, uncovered, until thickened, about 5 minutes, stirring occasionally., In an ungreased 13x9-in. baking pan, layer a third each of the following: chips, beans, beef mixture and queso dip. Repeat layers twice., Bake, uncovered, until heated through, 10-15 minutes. Top with tomatoes and, if desired, chives; serve immediately with sour cream on the side.