That’s a version of decadence, and I got what you meant originally, but most speakers in the north (well, United States, Wales, and Toronto, Ontario as those are who I talk to most) think more of the excessive indulgence stemming from moral decline.

“Oh that chocolate was so decadent” meaning “I feel like I slipped into gluttony and sin eating it it was so good”.

It’s kind of used as a mix between the two definitions depending on the context. It’s so interesting how language changes from place to place.