Heat the butter in a large pot or dutch oven over medium-high heat. Add the onion, carrots and celery; cook until soft (about 20 minutes), stirring occasionally.
Add the garlic and flour and cook an additional 3-4 minutes.
Add 1 cup pale ale while stirring to incorporate it smoothly. Stir until a thick paste forms (2-3 minutes).
Stir in the Worcestershire sauce, milk and chicken broth and bring to a boil, then reduce the heat and let it simmer for 10-15 additional minutes.
Remove the pot from heat and puree it with an immersion blender, or blend in a blender.
Return the pot to medium-low heat and slowly add the cheese while stirring. Do not allow the soup to boil.
Season to taste with salt and pepper.
Top with crutons and bacon bits before serving.