Prepare the Potatoes: Place the peeled and chopped Yukon Gold potatoes in a large pot, covering them with cold water by about 1 inch. Stir in 1 ½ teaspoons of kosher salt, then bring the water to a boil over medium-high heat. Once boiling, reduce to a gentle boil, cooking for 15-20 minutes until the potatoes are fork-tender. Drain the potatoes, return them to the hot pot, and let them steam for 1-2 minutes to remove excess moisture.

Make the Mashed Potatoes: In a small saucepan, warm ½ to ¾ cup of milk (or half-and-half) until just heated through. Add 4 tablespoons of room temperature unsalted butter to the hot potatoes and mash using a potato masher or ricer until smooth. Gradually stir in the warm milk and sour cream or cream cheese if using. Season the mash with ½ teaspoon salt and ¼ teaspoon pepper, adjusting to taste, covering and keeping warm on low heat as you move on to the chicken.

Season the Chicken: Pat 4 boneless, skinless chicken breasts dry with paper towels to ensure a good sear. In a small bowl, combine 1 teaspoon kosher salt, ½ teaspoon black pepper, ½ teaspoon garlic powder, and ½ teaspoon onion powder. Evenly sprinkle the seasoning over both sides of the chicken, pressing it in gently to enhance the flavor and ensure a delicious crust during cooking.

Sear the Chicken: Heat a large skillet over medium-high heat and add 2 tablespoons of olive oil along with 1 tablespoon of unsalted butter. When the butter has melted and starts to foam, add the seasoned chicken breasts in a single layer. Sear the chicken for 4-5 minutes on each side, achieving a golden brown color and an internal temperature of 68-70 °C (155-160 °F). Transfer the chicken to a plate, covering loosely with foil, and reduce heat to medium.

Start the Glazed Carrots: In a medium skillet, combine 450-500 grams of sliced carrots, 2 tablespoons of unsalted butter, brown sugar or honey, ¼ cup of water or orange juice, ¼ teaspoon salt, and ⅛ teaspoon black pepper. Bring this mixture to a simmer over medium heat, then cover and cook for 6-8 minutes until the carrots are just tender. Remove the lid and continue cooking for another 3-5 minutes, allowing the liquid to reduce into a glossy glaze.

Make the Creamy Herb Sauce: In the same skillet used for the chicken, lower the heat to medium and add the remaining 1 tablespoon of unsalted butter. Add the minced shallot and cook for 1-2 minutes until translucent, then stir in the minced garlic and cook for an additional 30 seconds. Pour in ½ cup of dry white wine or low-sodium chicken broth and simmer for 2-3 minutes until reduced by half, creating a flavorful base for the creamy herb sauce.

Finish the Sauce: Stir in 1 cup of low-sodium chicken broth, 1 cup of heavy cream, Dijon mustard, and the remaining ½ teaspoon of black pepper. Let this mixture simmer for 4-6 minutes until it thickens slightly. If using Parmesan cheese, fold it in at this stage. Finally, lower the heat and mix in the chopped parsley, chives, thyme, and basil, tasting and adjusting seasoning with salt and optional lemon juice for brightness.

Combine the Chicken with Sauce: Nestle the seared chicken breasts back into the creamy herb sauce, spooning the sauce over each piece. Allow the chicken to simmer on low heat for 4-6 minutes or until the internal temperature reaches 74 °C (165 °F). Turn off the heat and let the chicken rest in the sauce for 3-5 minutes, allowing the flavors to meld beautifully.

Plate the Dish: Give the mashed potatoes a final stir, adding a splash of warm milk for creaminess if desired. Spoon a generous mound of mash onto each plate, placing a chicken breast alongside or on top. Ladle the creamy herb sauce over both the chicken and potatoes, and serve a portion of glazed carrots on the side. Garnish with additional chopped herbs for a delightful finish to your Creamy Herb Chicken with Mashed Potatoes and Glazed Carrots.