There's a story that says that this dish was served to Napoleon on the day he defeated the Austrians on the battlefield near the village of Marengo in northwest Italy, mid-June 1800. The original recipe contained chicken cooked in oil, tomatoes, a little water, and garlic. The chicken was served with local steamed crayfish and fried eggs as garnish. Back in France, the dish became popular with the addition of mushrooms, thyme, and white wine. If you'd like, you can add uncooked crayfish or shelled uncooked shrimp in the last 10 minutes with the mushrooms. You can also substitute chicken breasts or chicken parts, skinned or unskinned.