Chicken Pot Pie

Melt one tablespoon unsalted butter with one tablespoon extra-virgin olive oil in large heavy skillet over medium-high heat. Add chopped onion and sauté until golden, seven to eight minutes. Add sausage; stir to combine. Add sliced mushrooms; sprinkle with salt and pepper. Sauté until browned and tender, about four minutes. Add mixed vegetables; cover and cook until carrots soften slightly, about two minutes. Add leftover vegetables, if desired. Add diced chicken, gravy, and chopped fresh thyme. Bring filling mixture to boil; reduce heat to low and simmer to thicken if necessary. Season to taste with salt and pepper. Mix in petits pois peas and chopped parsley. 

Refrigerate filling until cool, about 30 minutes. Divide filling among six individual baking dishes. 

Roll out pie crusts and cut slightly larger than individual baking dishes. Lightly brush rim of filled dishes with egg wash. Place crust atop each dish. Pinch dough rim to seal crust all around. Preheat oven to 400°F. Lightly brush top of pies with egg white to glaze. Make three to four quarter-inch slits in center of pies to allow steam to escape. 

Bake pies until crust is golden and filling is bubbling, 30 to 35 minutes. Remove from oven and let cool 10 minutes. 

Chicken Gravy

Pour broth into a large sauce pot over medium-high heat, bring to a boil; reduce heat to low and simmer until mixture has reduced by half, to three cups. 

Heat oil in a skillet over medium-high heat. Add onion; sauté five minutes. Add celery and garlic; sauté five minutes. Evenly sprinkle with flour; stir well, being sure to break up any clumps. Cook three minutes, stirring constantly. Remove from heat and deglaze with two tablespoons reduced broth; whisk well. Add two additional tablespoons broth; whisk well. Repeat until flour has absorbed liquid and is the consistency of pancake batter; add to remaining reduced chicken broth and whisk until smooth. Add any accumulated pan juices. Bring to a simmer over medium heat, skimming any foam or fat that rises to surface. Reduce heat to low and simmer 20 minutes, stirring often along bottom to release any settled roux (this will burn if allowed to sit unstirred). Taste; adjust seasoning with salt, pepper, and hot sauce. Strain through a colander lined with cheese cloth, if desired.  Keep warm until needed.