I made peanut butter cups a couple times in Italy (including once for a class pot luck, pictured alongside some brownies below) and I’m currently in the last step of making them right now (freezing). They always go over well because A) they seem impressive but are shockingly easy to make and B) they are a perfect one or two bite sweet treat to pop in your mouth!
I use this recipe, though this time I used half milk and half semi-sweet chocolate. I also found Italy to be lacking in mini muffin liners, so there I made them with small plastic cups, about the size of Dixie cups. The cups lacked the cute ridged look of a muffin liner but it was easier to paint the chocolate on because the plastic was so much sturdier and the pbs were easier to remove from plastic than paper. I also don’t have a paintbrush, but I find that the back of a spoon works just fine.
Good luck with your cups!