Combine hominy, garlic, and jalapeno in a saucepan. Bring to a boil, reduce heat, and simmer until hominy is tender, 15 to 20 minutes. Strain out liquid and pour hominy mixture into baking dish. Stir sour cream and butter into hominy mixture; top with Cheddar cheese.
Bake in preheated oven until cheese melts, about 25 minutes.
