Preheat the oven to 375 degrees Fahrenheit (190 degrees Celsius).

In a large bowl, combine the chicken and potatoes. Drizzle with 1 tablespoon of olive oil, toss to coat, and season with salt, pepper, and Italian seasoning blend or Herbs de Provence. Make sure the potatoes are cut evenly to ensure they cook at the same rate.

In a large skillet over medium heat, melt 2 tablespoons of butter. Add 1 tablespoon of olive oil and mix well. Using a combination of butter and oil helps achieve a nice sear on the chicken.

Place the chicken on one side of the skillet and the potatoes on the other side. Cook undisturbed for 3-4 minutes, then flip the chicken and cook for another 3-4 minutes until browned on both sides. Transfer the chicken and potatoes to a plate and cover to keep warm.

In the same skillet, melt 1 tablespoon of butter over medium heat. Add minced garlic and cook for 1 minute until fragrant. Be careful not to burn the garlic, as it can turn bitter.

Stir in the chicken broth and Dijon mustard, then whisk in the heavy cream, salt, and pepper.

Return the chicken and potatoes to the skillet, tossing them in the sauce to prevent drying out in the oven. Make sure everything is well-coated with the sauce for maximum flavor.

Transfer the skillet to the preheated oven and bake for 15-20 minutes until the chicken is cooked through and the potatoes are fork-tender.

Spoon the Dijon sauce from the skillet over the chicken and potatoes, garnish with cracked black pepper and fresh herbs if desired, and serve.