In a 6-quart sauce pot, over medium heat, melt butter. Add bacon and cook until well browned. Add onions, salt and pepper. Stirring occasionally, cook until tender (about 5 minutes). Add celery and cook an additional 5 minutes. Add potatoes and chicken stock. Bring to a boil then reduce heat to low. Cover and gently simmer until potatoes are soft (about 45 minutes). Turn off heat and puree with immersion blender until smooth. Stir in heavy cream and beer. Season to taste with salt and pepper. Finish with fresh thyme.
Recipe courtesy of Christian's Bistro in Plover, Wisconsin