Rinse squash and trim off stem ends. Set on a rack over about 1 inch boiling water in a 14-inch wok or 5- to 6-quart pan. Cover and steam over high heat until vegetables are tender when pierced, about 8 minutes.
In an 11- to 12-inch frying pan over high heat, melt butter. Add squash and thyme. Shake pan, gently mixing ingredients until butter begins to brown, 2 to 3 minutes. Season to taste with salt and pepper.
Nutritional analysis per garnish serving.