Heat butter in a large saucepan, add bacon and cook until fat renders and bacon is crispy. Remove bacon with a slotted spoon, drain on paper towels and set aside for garnish. To bacon fat add yellow, red, and white onions and shallots. Cook until they begin to wilt. Add leeks and scallions and cook for 3 minutes. Dust flour over, and stir and cook until flour turns golden. Add stock, bring to a boil and reduce heat. Simmer for 30 minutes. Add cream and season to taste with salt and pepper. Pour about one-third of soup and solids into a blender or food processor and purée, or pulse with an immersion blender. Reheat and serve garnished with bacon and chives. Garnish with a spoonful of onion marmalade, if desired.
Yield: 4 servings