Pat the chicken breasts dry with paper towels and season generously with salt and pepper on both sides.

In a small bowl, combine the minced garlic, chopped parsley, and thyme. Rub the mixture all over the chicken breasts and let rest at room temperature for 10 minutes.

Heat the olive oil in a large skillet over medium-high heat until shimmering. Add the chicken breasts and sear without moving for 5–6 minutes until a deep golden crust forms.

Flip the chicken and cook another 5–6 minutes. Add the butter to the skillet and baste the chicken with the melted butter and pan juices.

Cook until the internal temperature reaches 165°F, then transfer the chicken to a plate and tent loosely with foil.

In the same skillet, add the brown sugar and balsamic vinegar. Stir over medium heat for about 2 minutes until the sugar dissolves and begins to caramelize.

Pour in the chicken broth, scraping up any browned bits from the pan. Simmer for 5–7 minutes until the sauce reduces by half and becomes slightly syrupy. Adjust seasoning with salt and pepper if needed.

Meanwhile, peel and cut the potatoes into evenly sized chunks. Place in a large pot, cover with cold salted water, and bring to a boil. Reduce to a simmer and cook 15–20 minutes until fork-tender.

Drain the potatoes well and return them to the pot. Add the butter and heavy cream, then mash until smooth and creamy. Season with salt and pepper to taste.

To serve, spoon mashed potatoes onto plates, top with a chicken breast, and drizzle generously with the pan sauce. Garnish with additional fresh herbs if desired.