What you need:
360 g white chocolate chopped coarsely
½ cup (140g) smooth peanut butter
400 g dark chocolate chopped coarsely
Tip for coarsely chopping chocolate - bash chocolate with a meat mallet while still in its wrapping
Melt white chocolate in a bowl over a pot of simmering water.
Cool for 5 minutes then add peanut butter, stir until smooth.
Melt the dark chocolate the same way. Cool slightly
Drop alternate spoonfuls of the white chocolate mixture and dark chocolate mixture into a small pan you greased and lined with parchment paper earlier. Gently shake pan to level mixture. Can you tell I didn't wait long enough for the dark chocolate to cool? 
Then drag a skewer back and forth through the mixture several times for a marbled affect.
Now for the hard part: Let stand at room temperature for 2 hours or until set.
If you're impatient like me, you can stick it in the fridge.
When it has set, cut into small squares.
Yummy 
It's delicious and looks like you spent more than 20 minutes on it.
I have to admit it looked much prettier the other times I made it. Makes a great gift too.
i missed your recipes. 
! How I wish I had a piece of this right now. I'm having to resort to my peanut butter filled chocolate kisses from Christmas!
Btw., I never knew how to melt chocolate until you explained..putting a bowl over a pot of simmering water. Thank you so much!
Oh my. Chocolate and peanut butter - my favorite combo!
I will have to make my chocolate-peanut butter spiders and write up a blog.