Rúgbrauð: Icelandic Thunder Bread

I was very taken with the bread we were served in Iceland, so I've looked out a recipe and baked some. It's very rich, made with buttermilk, and tastes delicious. I'm not sure the Icelandic folk would be impressed, since this loaf erupted in the middle, like a volcano. But it's not a bad first attempt.

Baked with the help of my lava stones.