adverb, noun which may take the genitive case particle 'no'
surprisingly; astonishingly; wonderfully
Expresses that something is so much so that it causes surprise; often used with adjectives or verbs to mean 'surprisingly ~' or 'so ~ that one is amazed'.
このケーキはびっくりするほどおいしい。
This cake is surprisingly delicious.
彼はびっくりするほど早く走る。
He runs astonishingly fast.