Source: Cooks Illustrated Jan & Feb 2012
- 1¼ cups (6¼ oz) all-purpose flour
- ½ cup (2¼ oz) whole-wheat flour
- 1 T sugar
- ¾ tsp salt
- 10 T cold unsalted butter, cut into ½" pices
- 7 T ice water
- 1 tsp white vinegar
- 1 pound shiitake mushrooms (or a combination shiitake and baby bella), sliced thin
- 5 tsp olive oil, divided
- 1 lb leeks, light-colored parts only, sliced ½" thick and washed
- 1 tsp minced fresh thyme
- 2 T crème fraîche or sour cream
- 1 T Dijon mustard
- salt and pepper
- 3 oz (¾ c) Gorgonzola cheese, crumbled
- 1 large egg, lightly beaten
- Kosher salt
- 2 T minced fresh parsley
Combine flours, sugar, and salt in bowl or food processor. Add butter and process or use pastry blender until it forms pea-sized pieces. Sprinkle water and vinegar over mixture. Fold together until it forms a loose, shaggy mass, with some dry flour remaining. Transfer to a large square of plastic wrap and wrap tightly, pressing into a 4" square. Refrigerate 45 minutes.
Transfer dough to a lightly floured work surface. Roll into an 11"x8" rectangle (hint: have a sheet of paper nearby to help you estimate the size). Fold in thirds like a letter, using a bench scraper if needed. Turn dough 90 degrees and repeat. Turn once more and repeat. After this last fold, fold dough in half, forming a 4" square. Press top of dough to seal fold. Rewrap in plastic and chill for 45 minutes (up to 2 days).
Place mushrooms in covered bowl and microwave until tender, 3-5 minutes. Drain and return to bowl. Meanwhile, heat 1T oil in a large skillet over medium heat; add leeks and thyme, cover and cook, stirring occasionally, until leeks are tender and begin to brown, 5-7 mins. Transfer to bowl with mushrooms. Stir in crème fraîche and mustard. Salt and pepper to taste.
Place pizza stone (optional) on lower-middle oven rack and heat oven to 400º. Let dough stand at room temperature 15 minutes. Roll out on generously floured surface to a 14" circle. Transfer to parchment-lined baking sheet. Brush top of dough with 1 tsp oil. Spread half of filling over dough, leaving 2" border; sprinkle with half of Gorgonzola; repeat layers. Drizzle 1 tsp oil over filling. Fold edges of dough up over filling, working in sections and pressing gently to seal folds. Brush dough with egg and sprinkle with salt.
Lower oven temp to 375º. Bake until crust is deep golden brown and filling begins to brown, 35-45 minutes. Remove from oven; cool on a baking rack for 10 minutes. Transfer to cutting board, sprinkle with parsley, and serve.