Chicken Potpie with Savory Crumble Topping

1½ pounds boneless, skinless chicken breasts

3 cups low sodium chicken broth

2 tablespoons vegetable oil

1 medium onion, chopped fine (about 1 cup)

3 medium carrots, peeled and cut crosswise into ¼-inch slices (about 1 cup)

2 small celery ribs, chopped fine, about ½ cup

Kosher salt and ground black pepper

10 ounces cremini mushrooms, trimmed and sliced thin

1 teaspoon soy sauce

1 teaspoon tomato paste

4 tablespoons butter

½ cup flour

1 cup whole milk

2 teaspoon lemon juice, fresh

3 tablespoons minced fresh parsley leaves, divided

¾ cup frozen baby peas

Topping

2 cups flour

2 teaspoons baking powder

¾ teaspoon salt

½ teaspoon ground black pepper

⅛ teaspoon cayenne pepper

6 tablespoons butter, cut into ½-inch cubes and chilled

1 ounce parmesan cheese, finely grated, about ½ cup

¾ cup plus 2 tablespoons heavy cream

For the chicken: Bring chicken and broth to simmer in covered Dutch oven over medium heat. Cook until chicken is just done, about 8-12 minutes. Transfer cooked chicken to large bowl. Pour broth through fine-mesh strainer into liquid measuring cup and reserve. Do not wash Dutch oven.Meanwhile, heat oven to 450 degrees. Line a rimmed baking sheet with parchment paper or a silicone liner.For the topping: Combine flour, baking powder, salt, black pepper, and cayenne pepper in large bowl. Sprinkle butter pieces over top of flour. Using fingers or pastry blender, rub butter into flour mixture until it resembles coarse cornmeal. Stir in cheese. Add cream and stir until just combined. Crumble mixture into irregularly shaped frac12;- to frac34;-inch pieces onto prepared sheet and bake until fragrant and starting to brown, 10-13 minutes. Set aside.For the filling: Heat 1 tablespoon oil in the empty Dutch oven over medium heat until shimmering. Add onion, carrots, celery, frac14; teaspoon salt, and frac14; teaspoon pepper; cover and cook, stirring occasionally, until just tender, 5-7 minutes.While vegetables are cooking, shred chicken into small, bite size pieces. Transfer cooked vegetables to bowl with chicken; set aside.Heat remaining tablespoon oil in empty Dutch oven over medium heat until shimmering. Add mushrooms; cover and cook, stirring occasionally until mushrooms have released their juices, about 5 minutes. Stir in soy sauce and tomato paste and increase heat to medium-high. Cook, stirring frequently, until liquid has evaporated, mushrooms are well browned, and dark fond begins to form on surface of the pan, about 5 minutes. Transfer mushrooms to bowl with chicken and vegetables. Set aside.Heat butter in empty Dutch oven over medium heat. When foaming subsides, stir in flour and cook 1 minute. Slowly whisk in reserved chicken broth and milk. Bring to simmer, scraping bottom of pan with wooden spoon to loosen brown bits, then continue to simmer until sauce fully thickens, about 1 minute. Season to taste with salt and pepper. Remove from heat and stir in lemon juice and 2 tablespoons parsley.Stir chicken-vegetable mix and peas into sauce. Pour mixture into 9-by-13-inch baking dish. Scatter crumble topping evenly over filling. Bake on rimmed baking sheet until filling is bubbling and topping is well browned, 12-15 minutes. Sprinkle with remaining tablespoon of parsley and serve.Serves six.