Peanut butter cups seems easy enough to make, but here's a few tips/techniques to make it easier/better

you will need:

chocolate- i used hershey's bars since i can measure it by simply using the smaller bars
peanut butter- i used natural, crunchy peanut butter with some of the oil drained off (it'll separate if you let it sit for a few days; then just pour off it into some stir fry you're about to make!)
silicone cupcake cups
a pot of boiling water
a small plastic (or maybe metal) spoon

Step 1: Melt the Chocolate

place two of the small bars of chocolate into a cupcake cup, and place that in the boiling water
after a while, it'll begin to soften, and you can spread it out.

take one cupcake cup out of the boiling water (use pliers!), and press the chocolate down and out
make sure to work quickly (small batches), and to create "walls"

Step 2: Add Peanut Butter

Use a spoon, and place it in the center of the "base"
make sure the peanut butter doesn't touch the walls, otherwise you won't have a smooth, uninterrupted peanut butter cup!

not to little, not too much. you have to flatten it a bit. it's just a matter of trial and error before you find out how much peanut butter works for you

Step 3: Freeze

this step is simple enough, put the cups in the freeze. but it's important!
this will help keep the peanut butter from getting all goopy when you go to the next step

Step 4: Top It Off With Baked Chocolate

put several bars of chocolate in the oven at 350 F (about 180 C); my hypothesis (probably incorrect) is that this melts the chocolate better, so that it's more viscous and can be spread more easily.

Step 5: Enjoy!

i kept these in my freezer, and blended one into a protein shake.
not sure how long they'll keep, or whether they're too soft in the fridge, or countertop- though, i keep bot peanut butter and chocolate in the pantry, and they last just fine.