Grape, Fontina & Rosemary Folded Schiacciata

Method

1. 1Make the gelWhisk the psyllium and yeast into the warm water. Rest 5 minutes until it sets into a thick gel.
2. 2Mix the doughWhisk the flours, starch and salt. Add the gel, yogurt and 1 tbsp oil. Mix 2 to 3 minutes into a smooth, soft, slightly tacky dough.
3. 3RiseCover and rise somewhere warm for 1 hour, until puffy and about 1.5x.
4. 4PrepHeat the oven to 450°F (230°C), rack in the lower third. Line a half sheet pan with parchment and coat with 1 tbsp oil. Toss the grapes with rosemary and a pinch of salt.
5. 5Fill and foldWith oiled hands, press the dough into a rough 25 × 35 cm rectangle. Scatter all the fontina and half the grapes over the middle and right thirds. Using the parchment, fold the left third over the middle, then the right third over the top. Pinch the edges and press back out to about 1.5 cm thick.
6. 6Dimple and topRest 20 minutes. Drizzle with 2 tbsp oil and dimple deeply. Press in the remaining grapes cut-side up, then scatter feta, walnuts, flaky salt and pepper.
7. 7BakeBake about 30 minutes, until deep golden, grapes slumped, and 205°F (96°C) inside.
8. 8CoolCool on a rack at least 15 minutes before cutting.