Add the un-drained tofu, eggs, sugar substitute, and vanilla to a blender, and blend until smooth and creamy. With the motor still running, slowly add the melted butter. Continue to blend for 1 minute. Pour the contents from the blender into the prepared baking dish and sprinkle with the nutmeg. Place the baking dish into the oven, and bake for 20-25 minutes or until the edges puff but the center remains soft.