Blend together coconut milk, maple syrup, salt and cocoa powder until well incorporated.
Pour about 2-3 tsp of chocolate mix into the bottoms of 8 tin wells. You just need enough to form the base of the peanut butter cup.
Freeze for about 15 minutes. Remove from freezer and add 1/2 TBS peanut butter atop each chocolate base. If the peanut butter is too thick to work with, you could heat some in the microwave for about 10 secs, just enough to make it more pliable.
Pour the remaining chocolate mix on top of the peanut butter to completely cover. Freeze again.
They should be ready in 20 minutes. Keep in freezer until ready to eat!