Preheat the oven to 350°F (177°C). Spray a 9×13-inch baking dish with cooking spray and set aside. In a medium bowl, combine the sour cream and cream cheese until smooth. Spread the mixture evenly in the bottom of the prepared dish.
Heat refried beans in a small saucepan over medium-low heat and stir until warmed through. Spread the beans over the cream cheese mixture.
Top with lettuce, tomatoes, and cheese. Pour salsa evenly over the top of the dish.
Bake for 20 minutes or until cheese is melted and bubbly. Serve hot with tortilla chips or warm corn tortillas.