In a manner related to or characteristic of baking; in the way that something bakes.
From 'baking' (present participle of 'bake' from Old English 'bacan') with the adverbial suffix '-ly' (from Old English '-līc'), forming an adverb from the gerund.
Adverbs like 'bakingly' are rare in modern English but show how flexible our language is—you could theoretically describe any hot, transformative process as happening 'bakingly'!
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