Heat oven to 375°. Cut squash in half and scoop seeds. Place on a cookie sheet and brush with small amount butter and season with salt. Place thyme sprig in each half and bake for 15 minutes. Meanwhile, mix together apples, remaining melted butter, sugar and cinnamon. Remove squash from the oven. Fill each squash with apple mixture. Put them back in the oven for 15-20 minutes more, or until squash and apples are soft and caramelized.