Melt the butter or margarine in a 4 1/2 quart soup pot over medium heat. Add the onion, garlic and Worcestershire sauce and stir well. Add the beer and raise the heat to high and boil for 3 minutes to evaporate the alcohol. Add the chicken broth and bring the soup back to a boil. Lower the heat to medium-low and simmer.
Combine the cornstarch with 3 tablespoons water and stir until smooth. Set aside.
Add the half-and-half and shredded cheese to the soup. Stir constantly until the cheese melts. Then stir in the cornstarch mixture. Stir constantly until the soup is thick, about 2 minutes. Serve garnished with bacon bits.
