phrase + 给 + target + verb In the link below, the wiki page talks about 给 in this structure.

Subj. + 给 + Target + [Verb Phrase]

https://resources.allsetlearning.com/chinese/grammar/Verbs_preceded_by_%22gei%22

But I don't understand 晚饭妈妈做了面条给我们吃。 

The part before 给 is not a subject. Rather, it's a complete sentence. How would you explain this grammar?

Thanks.
It is a [topic + comment/ opinion] grammar structure 

晚饭 (dinner) is a topic

妈妈做了面条给我们吃。(mother made noodle for us to eat)  is a comment

The comment here is a basic [Subject +V + object]


You can replace the topic, e.g. Change 晚饭 to 午餐 and write "午餐妈妈做了面条" = "(for) lunch, mom made noodle"
You can replace the comment, e.g. Change 面条 to 饺子 and "晚饭妈妈做了饺子" = "(for) dinner, mom made dumplings"


Similar example:

Topic: 工作 (works)

Comment: 很难找到 (very hard to find)


Topic + comment sentence: 工作很难找到 (works are very hard to find )
SVO sentence: 很难找到工作 (it is hard to find works)


Using [topic + comment sentence] emphasize the topic