Mix, but do not whip, all ingredients except snails. Heat mixture in large skillet. Add snails and simmer 10 to 15 minutes, allowing liquid to cook into snails.
Preheat oven to 350 degrees.
Put small amount of butter mixture into bottom of each shell. Insert snail using end of fork. Top with additional butter mixture.
Continue until all shells are filled, placing them in flat baking dish as they are completed. Pour remaining butter mixture over snails and heat until bubbling, about 10 minutes.