In a large skillet, melt 1 tablespoon of unsalted butter and 1 tablespoon of olive oil over medium heat.

Add the chicken breasts to the skillet and season with poultry seasoning, kosher salt, and black pepper. Cook until browned on all sides and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.

In the same skillet, melt 3 tablespoons of unsalted butter. Stir in the flour and cook for 1-2 minutes to create a roux.

Gradually whisk in the low-sodium chicken broth, ensuring there are no lumps. Bring to a simmer and cook until the sauce thickens, about 3-5 minutes.

Stir in the fresh thyme, additional black pepper, and kosher salt. Return the cooked chicken to the skillet and coat with the gravy.

Serve the chicken and gravy over hot mashed potatoes and top with a dollop of Greek yogurt or sour cream if desired.