Peanut butter sandwich cookies with milk chocolate filling + two favorite Tumblrs

I’ve been obsessing with sandwich cookies lately – I want to bake each and every recipe for sandwich cookies I see (and no, I haven’t forgotten about biscotti, believe me). :)
I’d planned making one of Martha’s fabulous cookies but the jam I had around was very chunky – the jam is actually quite good but not thin enough for filling the cookies. I turned to the Karen DeMasco’s wonderful book and