Slice chicken horizontally without cutting all the way through to create a butterfly breast. Place chicken on cutting board with sheet of plastic wrap over top. With a meat mallet, gently pound chicken breast to even out the thickness of breast.

Mix the prosciutto ham, Gruyere cheese and thyme together and evenly spread onto all of the chicken breast. Roll each of the breasts up into a roulade and seal the seam with a tooth pick.

In a bowl, whip together egg and water to create an egg-wash.

On two separate plates, put flour and breadcrumbs. Season flour with black pepper.

Carefully dredge each chicken breast first into seasoned flour, then into egg-wash, followed by breadcrumbs.

Heat olive oil in an ovenproof sauté pan. Place chicken breasts in pan to brown. Cook for 2 minutes on one side, then flip each breast over. Place pan into a 350°F oven and cook until each chicken breast reaches 170°F internal temperature, about 15 minutes.

For the sauce, start by heating the olive oil over medium heat using a sauce pot. Sweat the garlic and onions for 3-4 minutes. Add the mushrooms and cook for another 5 minutes.

Stir in the flour to form a roux. Add the white wine and the chicken broth to the pan and bring to a boil. Then, reduce to a simmer and allow it to thicken. Finish the sauce with the heavy cream and the chopped fresh parsley.

To serve, the Cordon Bleu can be served whole or sliced. Place breast over rice or pasta with a green vegetable such as broccoli or asparagus with the sauce spooned over top.