Pat chicken cutlets thoroughly dry with paper towels. Season both sides with garlic powder, kosher salt, and coarse black pepper. Lightly dust with flour, tapping off any excess.

Heat olive oil and 1 tablespoon butter in a heavy 12-inch stainless steel or cast iron skillet over medium-high heat. Once shimmering, add chicken cutlets and sear undisturbed for 4 to 5 minutes per side until deeply golden and cooked to 165°F (74°C). Transfer cutlets to a warm plate and tent loosely with foil.

Melt remaining 2 tablespoons butter in the same skillet over medium heat. Add sliced mixed wild mushrooms in a single layer. Let sear without stirring for 3 minutes until deep golden-brown, then stir and cook for 3 more minutes.

Add minced shallot, minced garlic, and fresh thyme leaves. Sauté for 1 to 2 minutes until aromatic and tender, taking care not to burn the garlic.

Deglaze the skillet by pouring in the Halal chicken broth, scraping up all browned fond from the bottom of the pan with a wooden spoon. Whisk in Dijon mustard and heavy cream. Bring to a gentle simmer for 3 to 4 minutes until sauce thickens slightly.

Reduce heat to low and whisk in grated Parmigiano-Reggiano until smoothly incorporated into the sauce.

Nestle the seared chicken cutlets and any accumulated resting juices back into the skillet. Spoon the rich mushroom cream sauce over each cutlet and simmer for 2 minutes to reheat. Garnish with chopped flat-leaf parsley and fresh thyme sprigs. Serve hot!