01 - Pat the chicken breasts dry with paper towels and season both sides generously with salt and freshly ground black pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Place chicken breasts in the pan and sear for 5–6 minutes per side until golden brown and cooked through, reaching an internal temperature of 165°F. Remove chicken from the skillet and set aside on a plate, tenting loosely with aluminum foil to keep warm.
03 - Reduce the heat to medium. Add the finely chopped shallot to the same skillet and sauté for approximately 2 minutes until softened and fragrant, scraping up any browned bits from the bottom of the pan.
04 - Add the blueberries, fresh thyme leaves, chicken broth, balsamic vinegar, and honey to the skillet. Bring the mixture to a gentle simmer and cook for 5–7 minutes, stirring occasionally, until the blueberries burst and the sauce reduces slightly and thickens.
05 - Remove the skillet from heat and stir in the unsalted butter until melted and fully incorporated, creating a smooth, glossy sauce.
06 - Return the chicken breasts to the skillet, turning to coat evenly with the blueberry-thyme sauce. Let simmer for 1–2 minutes to heat through. Transfer to serving plates, spooning additional sauce over each portion. Garnish with fresh thyme sprigs and serve immediately.