Uttering adverbs are provided in this article. The words listed here are commonly found along with the verb uttering in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb UTTERING.
actually
continually
merely
occasionally
simply
Hope this word list had the uttering adverb you were looking for. In addition to adverbs used with uttering, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.