Preheat the oven to 350F/180C.
In a large bowl combine sour cream (you can use low-fat and although it will separate it will taste the same, I've used both full fat and low fat with the same results), corn, black beans, both cheeses, chopped cilantro, spring onion and minced garlic.
Mix gently, the mixture will be quite solid.
Empty the contents into a 9" baking dish and bake for 15 minutes until cheese is melted and the dip is runny.
Serve with tortilla chips, bread, crackers or raw veggies.