Start by cleaning and slicing the mushrooms. Season the chicken breasts with salt and pepper. Place the flour in a shallow dish and coat each chicken breast lightly with flour.

In a large skillet, melt the butter over medium heat. Add the sliced mushrooms and a pinch of salt. Cook until they are browned and tender, about 5-7 minutes. Remove the mushrooms from the skillet and set them aside.

In the same skillet, add olive oil and increase the heat to medium-high. Add the floured chicken breasts and sear on both sides until golden brown, about 4-5 minutes per side. Remove the chicken and set it aside with the mushrooms.

Lower the heat and pour in the beef broth, scraping up any brown bits from the bottom of the skillet. Add the chicken bouillon, soy sauce, onion powder, mustard powder, thyme, and white wine. Stir well.

Return the chicken and mushrooms to the skillet. Bring the mixture to a boil, then reduce the heat and let it simmer for about 15 minutes.

In a small bowl, mix the cornstarch with a bit of cold water, then stir it into the skillet. Add the minced garlic and heavy cream, stirring until the sauce thickens. Cook for another 2-3 minutes before serving.