Clam Chowder with cream

1 lb potato , peeled 1/2 tablespoon butter 3/4 cup finely chopped onion 1 small garlic clove , very finely minced 1 cup half-and-half 1/2 cup whipping cream 4[...]

2 small onions , chopped 1 cup celery , chopped 2 tablespoons butter 1/4 cup butter 4 (6 ounce) cans minced clams (drained, save for broth) 4 (10 3/4 ounce)[...]