Based on the recipee from http://tartine-bread.blogspot.ca/  but with modification. Used blueberry (it is the season!) in the first one. Winning combination!
Which lead me to, mmm, chocolate and blueberry... I wonder.
So I added over 1/4 cup of cocoa powder to the mix. But as I was short on flour, I also added some whole wheat (go figure). Despite all the changes in the recipee, it turned out quite good! The crumb is not as developped, but you can definately taste the cocoa flavor.
Another day, anothe experiment!