Dissolve 1 tablespoon kosher salt in 4 cups cold water in a large bowl. Submerge chicken breasts and refrigerate for 15-30 minutes (not longer, as this is a quick brine).
Position an oven rack in the middle position and preheat to 375°F (190°C). Line a rimmed baking sheet with aluminum foil and place a wire rack on top. Lightly coat the rack with cooking spray.
Remove chicken from brine and pat thoroughly dry with paper towels. Rub with neutral oil and season with black pepper and garlic powder.
In a small saucepan, combine maple syrup, Dijon mustard, apple cider vinegar, soy sauce, olive oil, minced garlic, dried thyme, and cayenne (if using). In a separate small bowl, mix cornstarch with 1 teaspoon cold water to form a slurry, then add to the saucepan. Bring to a simmer over medium-low heat, whisking constantly for 3-4 minutes until slightly thickened. Remove from heat and divide into two portions: one for initial glazing and one for basting.
Brush the chicken breasts generously with about one-third of the glaze, coating all sides.
Place the chicken breasts on the prepared wire rack, ensuring they don't touch. Bake for 15 minutes.
Remove from oven and brush with another third of the glaze. Return to oven and bake for 10 minutes.
Brush with remaining glaze and continue baking until internal temperature reaches 165°F (74°C), approximately 5-10 more minutes. Total cooking time will be about 30-35 minutes, depending on the thickness of your chicken breasts.
Remove from oven and let rest for 5-7 minutes to allow juices to redistribute and internal temperature to stabilize.
Cut chicken against the grain and serve immediately, spooning any accumulated juices over the sliced meat.