I think I found a way to get to this level! When you're fighting N. Tropy and N. Brio there's some crates in the far distance just floating there in mid-air! I can't tell if they're jump crates or not but I think these crates are there for something; possibly to get you to the "Gone a bit Coco" level. I haven't figured out how to get over to them, but I think you can get there after you defeat N. Tropy by going over to the far side of the platform, opposite the crates, and let N. Brio launch you to them when he flops down on the platform.
AMAZING picture!!!! I love it!!!!