In a bowl mix together the peanut butter, powdered sugar, vanilla extract, and salt. It will form a sort of soft dough.
Melt the chocolate chips. I usually melt the chocolate in the microwave.
To make the peanut butter cups, use a chocolate mould or cupcake liners. Add just enough chocolate to the mould or cupcake liners to just cover the bottom.
Take a piece of the peanut butter dough and form a disc that is just smaller than the mould so that there is room for the chocolate to go around the edges. Put the peanut butter discs into each mould.
Now finish by pouring more chocolate over top so that the chocolate goes around the sides of peanut butter dough and covers the top. Repeat until you run out of chocolate and peanut butter dough.
Put in the fridge to cool and set for about 30 minutes. Once the chocolate has solidified again, you can pop them out of the moulds, or just trim the paper liners if you want to leave them protected.