Season chicken breasts evenly on both sides with salt, pepper, garlic powder, and dried thyme. Gently press the seasonings into the meat to ensure they adhere well.
Combine diced peaches, honey, apple cider vinegar, Dijon mustard, minced garlic, grated ginger, and red pepper flakes in a medium saucepan. Bring the mixture to a simmer over medium heat.
Reduce heat to medium-low and cook for 10-12 minutes until peaches soften and the mixture thickens slightly. For a smoother consistency, use an immersion blender to puree about half the mixture while leaving some peach chunks for texture.
Heat olive oil in a large skillet over medium-high heat. Add chicken breasts and cook for 5-6 minutes per side until golden brown and the internal temperature reaches 160°F (71°C).
Reduce heat to medium-low and pour ¾ of the peach glaze over the chicken. Turn the chicken to coat both sides, and continue cooking for 2-3 minutes until the glaze caramelizes slightly and the chicken reaches 165°F (74°C). Reserve the remaining glaze for serving.
Transfer chicken to a cutting board and let rest for 5 minutes before slicing. This resting period allows juices to redistribute throughout the meat.
Slice chicken against the grain and drizzle with the reserved peach glaze before serving.