Pat the 4 chicken breasts dry with paper towels. If they are thick, butterfly each breast or pound to an even 1/2-inch thickness using a meat mallet between two pieces of plastic wrap. This ensures even cooking.

Season both sides of each chicken breast evenly with 1 1/2 tsp kosher salt, 1 tsp black pepper, and 1 tsp garlic powder.

Flour & Sear

Place 3 tbs all-purpose flour on a shallow plate and lightly dredge each seasoned chicken breast, shaking off excess. Heat a large skillet over medium-high heat and add 2 tbs unsalted butter and 1 tbs olive oil until butter foams and begins to brown slightly.

Add the chicken breasts to the skillet (work in batches if needed so they aren’t crowded). Sear 3–4 minutes per side until golden brown and just cooked through (internal temperature 155–160°F / 68–71°C). Remove chicken to a plate and tent loosely with foil (residual heat will bring internal temp to 165°F). Keep pan juices in the skillet for the sauce.

Sauce

Reduce heat to medium. Add the finely minced shallot to the skillet and sauté in the pan juices for 1–2 minutes until softened and fragrant, scraping up browned bits from the bottom of the pan.

Pour in 1 cup dry white wine to deglaze the pan. Use a wooden spoon to scrape any fond and simmer until the wine is reduced by about half, approximately 3–4 minutes.

Stir in 1 cup chicken stock and bring to a gentle simmer. Let the mixture reduce for 4–5 minutes until slightly thickened.

Lower heat to medium-low and whisk in 1/2 cup heavy cream, 1 tbs Dijon mustard, and 1 tbs fresh lemon juice. Cook another 2–3 minutes until sauce is smooth and coats the back of a spoon. Taste and adjust seasoning with additional salt and pepper if needed.

Stir in 1 tsp fresh thyme leaves and 2 tbs chopped fresh parsley. Keep the sauce warm but do not boil vigorously once cream is added.

Cheese & Finish

Return the seared chicken breasts to the skillet, spooning some sauce over each piece. Arrange 2 slices of Swiss cheese (or equivalent shredded amount) on top of each breast.

Preheat your oven broiler on high (or set oven to 425°F / 220°C). Transfer the skillet to the oven (or place chicken on an oven-safe baking sheet) and broil for 1–3 minutes until the cheese is melted and lightly browned—watch carefully to avoid burning.

Remove the skillet from the oven. Sprinkle 1/4 cup grated Parmesan over the melted Swiss and let rest 1–2 minutes. Spoon extra sauce from the pan over the chicken, garnish with additional chopped parsley if desired, and serve immediately.