In a large saucepan, melt butter over low heat. Toss in garlic and saute 1 to 2 minutes, until slightly golden. Mix chopped tomatoes into pan. Stir in chicken stock, thinning with 1 to 2 tablespoons water if necessary. Cook over medium heat until bubbly. Stir in Vermouth and cook 5 minutes more. Mix in basil just before serving.