Melt butter in a heavy-bottom soup kettle. Add onions, garlic and saffron and cook over medium-low heat, stirring frequently, until onions are softened. Do not let onions brown.

Bring chicken stock to a boil. Add bread crumbs to onions and stir to mix thoroughly. Add chicken stock and stir again. Bring soup to a boil and immediately lower heat and simmer, covered, for 20 minutes.

Puree soup in a blender, food processor or fine-mesh food mill. Strain soup, discarding solids. Return to rinsed-out soup kettle. Add cream and lemon juice. Mix well and taste, adding salt and pepper if desired. May be served immediately, or chilled and served as a summer soup.