In a small bowl, combine the ingredients for the levain until well incorporated.
Cover and ferment at room temperature 8 hours.
Preheat the oven to 400F.
Remove the outer papery layers from the garlic, but leave the skins on.
Place the garlic in a square of foil and drizzle 1 TBSP olive oil on top.
Wrap the foil around the garlic and place the packet in the oven.
Roast for 1 hour, or until soft and beginning to turn golden.
Allow the garlic to cool enough to handle, then squeeze out the garlic cloves from their skins.
Mush the garlic with a fork, and mix together with the remaining olive oil and chopped rosemary.
In the bowl of a stand mixer with a dough hook, combine the fermented levain, the flour, salt, and about 85% of the water to start with. Mix on low speed until combined.
Increase the speed to medium and mix until you get a medium level of gluten development.
Add the remaining water and the garlic puree and mix until incorporated. The dough will be very soft and will not come together around the dough hook but it should have both strength and elasticity.
Transfer the dough to a well lightly oiled bowl.
Cover and allow to ferment for 4 hours at room temperature, with a fold at 30, 60, and 90 minutes.
Turn the dough out onto a lightly floured counter and divide into 2 pieces.
Shape them into loose balls and allow to rest, covered, for 20 minutes.
Turn the balls of dough over and gently round them into a smooth ball.
Make a small “X” on the top of each ball of dough and twist a garlic clove in the center.
Wet 3 or 4 parsley or cilantro sprigs and arrange them around the garlic.
Dust the loaves with flour and place them, decorated side down, into a linen lined basket.
Proof at room temperature, covered, for another 4 hours.
Preheat the oven and a baking stone to 425F, as well as prepare for your method of steam.
Turn the proofed loaves out onto a sheet of parchment paper and slash a circle about 1″ from the edge.
Slide the parchment paper onto the baking stone and bake for 10 minutes with steam, and then 25 without, until the loaves are golden brown.
Turn the oven off and leave the loaves in the oven, with the door cracked, for another 10 minutes.