Combine all of the ingredients except for the green onions in a large bowl. Mix with a hand mixer until combine, then pour into a large skillet or square baking dish.
Bake for 25-30 minutes until hot and bubbly. Stir, then sprinkle with the green onions, if desired, and serve with tortilla chips.
Alternately, you can mix all of the ingredients together except for the green onions and pour into a slow cooker. Cook on low for 1-2 hours until warmed through.
Notes
A crust may form on the top of the bean dip as it sits, but if you stir the dip well this will mix right back in.