Begin by patting the chicken breasts dry with paper towels. Split each breast horizontally into two thinner cutlets. Alternatively, you can place the chicken breasts between two sheets of plastic wrap and pound them to achieve an even thickness.

In a bowl, mix together flour, salt, pepper, and garlic powder. Set this mixture aside for later.

Next, heat 2 tablespoons of butter and 1 tablespoon of olive oil in a large skillet. Once the butter has melted, dredge 3 chicken cutlets in the flour mixture. Make sure to coat both sides and shake off any excess flour.

Add the coated chicken to the skillet and cook until it's nicely browned, this should take about 5 minutes. Flip the cutlets and cook for another 3-5 minutes. Remove the cooked chicken, place it on a plate, and cover it to keep warm. Repeat this step with the remaining chicken.

It's time to prepare the sauce. Add the remaining 2 tablespoons of butter to the pan and heat until it's fully melted. Add sliced mushrooms to the pan and cook without disturbing until the mushrooms are dark on one side. Stir and turn the mushrooms, and continue cooking until all moisture evaporates and the mushrooms are well browned.

Now, add the sliced shallots to the pan and cook until they soften and start to brown. Add minced garlic and sauté for 30 seconds or until it's fragrant.

Pour the wine into the pan to deglaze, ensuring you scrape the bottom. Add the thyme sprigs, chicken broth, Dijon mustard, and cream. Allow the mixture to boil and cook for 5 minutes.

Stir in the cornstarch solution, bring the sauce back to a light simmer, and add the chicken. Let it heat and simmer for 5 minutes or until the sauce thickens and the chicken is warmed through.

Remove the thyme sprigs, season the dish with salt and pepper according to your taste, and garnish with parsley or additional thyme.

Serve these flavorful Chicken Mushroom Cutlets with rice, potatoes, or noodles for a satisfying meal. Enjoy this delicious recipe that's bound to become a family favorite!