Chicken Breasts Stuffed with Brie and Caramelized Onions with Mushroom Sauce

For the chicken:

In a skillet over medium-high heat, warm canola oil and 2 tablespoons butter until hot but not smoking. Add onions and sauté, stirring constantly, until caramelized, about 20 to 25 minutes. Season with Kosher salt.

Preheat oven to 350°F. Open the chicken breast in the middle with a sharp knife, making a pocket. Pat chicken dry. Fill cavity with small piece of cheese, 1 tablespoon caramelized onions. Season with salt pepper and oregano. Fold over chicken over filling and secure with toothpicks. Dip chicken in egg, allowing excess to drip into bowl. Roll in breadcrumbs, shaking off excess. At this point you can cover the chicken with plastic and foil and freeze.

Place chicken (even in frozen) in baking dish. Pour 2 tablespoons melted butter or olive oil over chicken. Bake until cooked through, about 30 minutes.

For sauce:

Meanwhile, melt 1/4 cup butter in heavy large skillet over medium heat. Add the mushrooms and sauté until tender, about 8 minutes. Add wine and boil 3 minutes. Add stock and boil until liquid is reduced by half, about 6 minutes.

Remove from heat and add 4 tablespoons cold butter 1 piece at a time. Season sauce with salt and pepper to taste.

remove toothpicks from chicken. Cut rolls crosswise into 1/2-inch thick rounds. Fan on plates. Serve immediately, passing sauce on the side.