I'm on to something!
I take less water in the pot, sicne you can't take more coffee, in order to get a stronger brew.
Now, with my own "espresso blend", freshly roasted (right from the frying pan type of fresh) and my smallest moka pot that makes only one cup I just got the fattest crema I've ever seen in a moka pot before (and I've seen a few... ). It filled more than half the top part of the pot!
Best tasting cup of moka I've had in my life so far. I'll be able to beat it soon I think...