Levain is a sourdough bread, also known as pain au levain. In this version of Walnut Levain Bread the walnuts are toasted and give the tangy bread a bit more texture. This bread has the perfect chewy texture and goes great with a slab of butter and a warm soup.
Add the walnuts to a dry medium skillet set over medium-high heat. Toast until they become fragrant and slightly browned. Remove to a cutting board and coarsely chop. Set aside.
In a large bowl add the remaining ingredients and mix well to combine. Turn out onto a lightly floured surface and knead until the dough becomes elastic. Flatten out and place the chopped walnuts in the center. Knead until the nuts are well incorporated, about 10 turns. Spray a large bowl with cooking spray and add the dough ball. Lightly coat with cooking spray and cover the bowl with plastic wrap. Place in a warm, draft free, area for 90 minutes.
Divide the dough in half and form into balls. Place on a flour dusted parchment lined baking sheet and cover loosely with plastic and place in a warm, draft free, area for 1 hour.
Preheat oven to 425 degrees F. Bake the bread for 25-30 minutes. Remove from the oven and cool for 5-10 minutes before slicing.