Haha it is a popular tricky Chinese problem. 下 is a verb here, means "make". Thus the right one is "He(他) makes (下) pasta(面)". However, it will not only confuse you but also other Chinese people. We don't say it like this. You can say 他正在下面。下面means stew noodle(we don't have pasta in China). 做面means make the dough into noodles.