A cast iron pot with a lid does the trick. I put the empty pot in the oven as soon as I turn it on to 450 (about an hour before baking) so that the pot is hot when I drop the proofed dough in. Then I put the lid back on and stick the whole thing back in the oven right away to bake for 20 minutes, then remove the lid and bake for another 15 or so minutes to get it good and brown. When it's done it pops right out of the pot and should be brown and crusty and hollow sounding when tapped.
I used spelt flour and white bread flour (50/50) for this loaf and my own sourdough starter.