Faux-R-E-O's! Whoa...

Found on the Food & Wine site, Heavenly Chocolate Sandwich Cookies.

Simple recipe, but not perfection.

Flour, cocoa, salt, butter and sugar, mixed together. formed into an eight-inch square and chilled.

Cut the dough into quarters, then roll each piece into an eight-inch square; cut that into quarters, and then into quarters again (we're aiming for sixteen here, for the math-challenged). Bake and cool.

Here's where I felt the recipe got all stupid on me: using a wooden spoon, mix a stick a butter with a heck of a lot of powdered sugar...until thick and creamy.
What?

I mixed and mixed. I tried using a pastry cutter. I even brought out the electric mixer. And instead of becoming, as promised, thick and creamy, I got...crumbly.

I gave up, and was able to form, by hand, the filling into appropriate cookie-shapes.

The cookie was very dark, very chocolatey. It was also kind of crumbly (real word?). I was relieved when I only lost six.

The filling, however, was really good. It tasted like the filling of those trademarked cookies, ehem. Without all the shortening.

But still not perfect. Not quite what I'm going for. I'll have to hunt for a clone recipe, I suppose.

Oh, and speaking of those cookies that-shall-not-be-named: European readers...what can you tell me about the chocolate cookies sandwiching tasty white filling you get where you live?

I recently read in a news article that the CTSNBN sold in Europe have a non-trans fat filling (and a creamier one, at that), and a denser, darker, cookie. I'd love to hear your thoughts!