Could a Ukrainian explain what the cheese is doing in the butter?
American cheese is rather dry, only slightly moist, and there is no butter, or milk, or oil dripping from it.
It’s an idiom, meaning the bear feels very comfortable in the forest.
See my answer here for more details: https://www.duolingo.com/comment/23402987
Similar to the English "rolling in dough" or "living like a lord".
Comes from the way cheese is prepared (there is an optional stage when it's left to soak in butter).