Pat the chicken breasts dry. Heat olive oil in a large skillet over medium-high heat. Sear the chicken for 2-3 minutes per side, until golden brown. Place the seared chicken in the bottom of a 6-quart slow cooker.

In a medium bowl, whisk together the maple syrup, Dijon mustard, chicken broth, apple cider vinegar, garlic powder, onion powder, salt, and pepper.

Pour the sauce over the chicken in the slow cooker. Add the fresh thyme sprigs on top. Cover and cook on low for 4-5 hours or on high for 2-3 hours, until the chicken is cooked through and tender.

Carefully remove the chicken from the slow cooker and place it on a cutting board to rest for 5-10 minutes. You can slice or shred it as desired.

In a small bowl, whisk together the cornstarch and cold water to create a slurry. Whisk the slurry into the liquid in the slow cooker. Turn the slow cooker to high, cover, and cook for 15-20 minutes, or until the sauce has thickened.

Return the chicken to the slow cooker and toss to coat with the thickened sauce. Serve immediately.