bombastically

in a pompous or inflated way

Bombastically means with verbal padding: loudly, grandly, and with more stuffing than substance.

He announced the minor schedule change so bombastically that everyone expected a national emergency.

If bombast is padded speech and bombastic describes the style, bombastically is the manner: the way someone says it.

Use the stage image. The speaker enters with fog machine confidence, but when the smoke clears, the sentence may not have carried much meaning.