IPA: /ˈklɔɪ.ɪŋ.li/
KK: /ˈklɔɪɪŋli/
In a way that is overly sweet or rich, often to the point of being unpleasant.
The dessert was cloyingly sweet, making it hard to enjoy after a few bites.
Cloyingly → It is formed from "cloy" (from Middle English *cloyen*, meaning to satiate or to fill) and the suffix "-ingly" (meaning in a manner that). The word "cloyingly" describes something that is excessively sweet or rich to the point of being sickening.
Think of something that is so sweet or rich that it 'fills' you up ('cloy') in a way that is overwhelming — that's why cloyingly means excessively sweet.