makes one leaf-shaped loaf; adapted from Maurizio Leo's Sourdough Fougasse
Add starter, water, flours, and salt to mixing bowl. Using dough hook, mix until dough forms around the hook then continue mixing on medium speed for 4 or 5 minutes.
With mixer running on low speed, slowly drizzle in the olive oil and mix until incorporated into the dough. Mix on medium speed for a couple more minutes. Then scrape down sides of bowl with a curved-edge bench scraper or spatula, do one set of stretch-and-folds (pulling dough from bottom of bowl to top, working around the "clock" from noon, to 3:00, to 6, to 9, this series is one set). Cover bowl and let sit in a warm place for the duration of bulk fermentation, 3–4 hours doing 3 additional sets of stretch and folds at 30 minute intervals.
I set my bowl either on the back of my range on on top of the radiator. Another warm spot I learned about last winter when it was 20 below here in Montana, is in the oven with the oven light turned on, no heat.
At the end of bulk fermentation, your dough should be puffier than when you started. If not, let it go 30 minutes to an hour longer. This dough will stay firm, unlike the more jiggly dough for a more hydrated sourdough bread. That's by design, you're going to try to shape a leaf out of this after all.
Fit a piece of parchment to a half-sheet pan (13x8 inches) or use a Silpat liner or liberally olive oil the pan. Form the dough into a triangle-ish shape by pulling, patting, and gently nudging it into shape. Take care not to de-poof the dough too much. I do this directly on the parchment but alternatively, you can roll out on a flat surface lightly dusted with flour then transfer to the parchment.
Using a sharp knife, slash the dough in several places, gently pulling the dough to make your leaf-like design. Transfer the parchment/shaped dough onto the sheet pan with a quick, trusting, slide. Brush top of dough with olive oil, cover with plastic wrap, and let rest in a warm place to proof for 1.5–2 hours.
Preheat oven to 450°F during last 30 minutes of proofing.
Bake fougasse for 20–25 minutes until top is beginning to turn golden brown. Remove from oven and brush with additional olive oil. Best the day it is made but if you do have leftovers, they're great split and toasted for breakfast!