Preheat oven to 375°F. Arrange chips in single layer on 2 lightly greased foil-lined shallow baking pans, overlapping chips if needed to cover pan completely.
Mix refried beans, sour cream and Seasoning Mix in small saucepan. Cook on medium heat until heated through, stirring occasionally. Spread 1/2 of the refried beans mixture on each pan of chips. Sprinkle each with 1/2 of the cheese.
Bake 5 minutes or until cheese is melted. Sprinkle with tomatoes and green onions. Serve immediately with assorted toppings, if desired.