Preheat the oven to 350°.
In an oven-proof skillet melt 2 T. of butter with the olive oil over medium heat. Season the chicken with salt and pepper. Brown the chicken quickly on both sides and set aside.
To the same skillet, add two more T. butter, the sliced onions, salt and pepper to taste, and the pinch of sugar. Turn the heat to low and cook slowly for 20-30 minutes, stirring occasionally, until onion is beginning to caramelize.
Stir in the flour and cook for a minute or two while the raw taste cooks off. Add the wine and cook until the wine has reduced by half. Stir in the consommé, pepper, and thyme. Add the chicken back to the skillet, nestling the pieces among the onions. Put in the oven to bake for 20 minutes.
Meanwhile, melt the last 2 T. of butter and toss with the breadcrumbs or cracker crumbs. After the chicken has cooked in the oven for 20 minutes, top the chicken pieces with cheese, and sprinkle with the buttered crumbs. Return to the oven for 10-15 minutes or until the cheese is melted and the crumbs are brown. Serve the chicken and sauce over mashed potatoes or slices of toasted French bread.