Preheat the oven to 450 degrees.
Mix together the garlic, soy sauce, sesame oil, ginger, and red pepper flakes in a small bowl.
Place the bok choy on a baking sheet sprayed with cooking spray. Pour the sauce over the bok choy.
Roast the bok choy for 7-10 minutes, or until the stems are tender. Exact cooking time will depend on the size and thickness of the bok choy. Remove from oven and top with sesame seeds.