Meanwhile, in 3-quart saucepan, melt butter over medium heat. Add onion and garlic; cook 2 to 3 minutes, stirring occasionally, until onion is crisp-tender. Stir in flour; cook and stir until bubbly. Gradually stir in half-and-half, broth, sherry, salt and pepper. Heat to boiling, stirring constantly. Boil and stir 1 minute. Remove from heat and set aside.