Butter that's foaming in the pan, then whatever basic sandwich bread, then Norwegian "yellow cheese", sort of like a mild Gouda. The cheese itself is good but not that exciting, so a pinch of salt and this or that spice (BBQ spice, garlic powder, chili flakes) is good, or some more flavorful cheese. I like keeping it simple so the butter flavor doesn't get lost, though. Maybe cheat with a tiny bit of extra butter to finish.