self-importantlyadverb

self-importance | American Dictionary

self-importance
noun[ U ]
us/ˌself·ɪmˈpɔrt·əns/
the belief that you are more important or valuable than other people:
He strutted into the room, self-importance written all over his face.

self-important

adjectiveus/ˌself·ɪmˈpɔrt·ənt/
You are a self-important little twerp.