1 1/4 cups all purpose flour
1/2 tsp. salt
1/2 cup butter cut into 1/2 -inch cubes
3 Tbsp. or more ice water
1 egg yolk, whisked to blend with 1 Tbsp. water (for Glaze)
7 Tblsp. butter, room temperature, divided
5 Tbsp. all purpose flour
2 Tblsp.olive oil
8 oz. mushrooms sliced
1 cup chopped onion
1 cup 1/2-inch cubes celery
1 cup 1/2 inch cubes peeled carrots
1 1/2 Tbsp. thyme leaves or fresh thyme
1 garlic clove, minced
1 cup dry white wine
2 1/2 cups chicken broth
5 cups torn roast chicken
1 1/2 cups frozen green peas
1/3 cup whipping cream
1/3 cup parsley
For crust: Blend flour and salt in processor.Add butter and blend, using pulse until mixture resembles coarse meal. Add 3 Tbsp. ice water, blend until moist clumps form, adding more water by teaspoonfuls if dough is dry. Gather dough into ball, flatten into rectangle. wrap in plastic and chill at least 1 hr.
Heat oven to 425º. Roll out crust on floured surface to 12 by 8 inch rectangle. cut into 8 equal rectangles. Transfer to baking sheet,spacing apart. Pierce crust with fork, then brush with egg glaze. Bake until light golden. Run knife under crusts and cool on sheet.
Mix 5 Tbsp. butter and flour in small bowl until smooth. Melt 2 Tbsp. butter with oil in large wide pot over medium -high heat. Add mushrooms, onion, celery, and carrots. saute until vegetables start to soften and brown. Add thyme and garlic, stir for about 3 minutes. Add wine, boil until almost evaporated, about 3 minutes. Add 2 1/2 cups chicken broth, bring to simmer. Add butter-flour mixture, 1 tbsp. at a time. Whisk until incorporated and mixture boils. Reduce heat and simmer until sauce thickens, stirring often . Stir in peas,chicken,cream, and parsley. Bring to simmer. Season with salt and pepper. Cool slightly. Heat oven to 425º Transfer filling to 13 by 9 by 2 inch baking dish. Carefully place crusts atop filling bake until heated through. about 20 minutes.