I’ve experimented in the US since “real” kaffeost is hard to get ahold of, and I’ve found Wisconsin cheese curds to work the best.
For coffee, you'd likely want the one without other things in it ( https://carrvalleycheese.com/product/bread-cheese/ )
> In Finland there is a cheese called Juustoleipa. This translates into cheese bread. We make ours different but better with oven baking it until it has a browned crusty top. Pop it in your oven or microwave until it glistens. Serve it with your favorite dip as a delicious snack. Good as is!
Note the pairings recommended:
> Honey, jam, syrup, coffee
It looks like you can order it from there too.