Saute onions in butter & garlic. Add salt & pepper once onions begin to soften and appear transparent, add sugar. Carmelize till lightly browned and add sherry & Worchestershire sauce.
In blender, add onion mixture and chunks of cheese. Add Cream cheese and blend together. Fill hollowed out sourdough bread and bake in oven for approximately 30 minutes at 350°F until heated through.