Saute onions in butter and oil until onions are transparent, but not
well browned. When tender, turn heat to lowest point and sprinkle with
flour, stirring vigorously. Pour into Dutch oven and stir in broths.
Heat thoroughly and divide among 8 oven-proof bowls. Float a slice of
bread atop each serving. Mix equal parts of cheese to smooth paste and
spread over bread. Place all bowls on oven rack 4" from broiler heat and
broil until cheese melts. Serve at once. Leftover soup freezes well up
to 6 months. Source: Gloria Pitzer
