1 ½lbschicken, (approx. 3 chicken breasts....I used 2)
2cupslow-sodium chicken broth, (or 1-14.5oz can Swanson's)
1Tbspolive oil
1onion, chopped (1 cup)
3-4carrots, peeled & sliced (1 cup)
2-3ribs celery, chopped (½ cup, but I used 1 cup)
4Tbspbutter
⅓cupall-purpose flour
1cupmilk
½tspsalt
½tsppepper
1tspdried thyme
¾cupfrozen peas, (I used 1 cup b/c I like vegetables)
Crumble Topping:
2cupsall-purpose flour
2tspbaking powder
¾tspsalt
½tsppepper
⅛tspcayenne pepper
6Tbspbutter, cut into ½-inch cubes & chilled
¾cupfreshly grated parmesan cheese
1cupheavy cream or milk, (I used skim milk)
Instructions
Simmer chicken in broth in a large pot; cook till just done, about 10-12 minutes. (If you plan in advance you can slow cook in the crockpot on high for 3 hours or low for 5 hours.) Transfer chicken to a medium bowl. Pour broth through fine-mesh strainer into a liquid measuring cup & reserve. Save empty pot for later.
Preheat oven to 400˚F. In a large bowl, combine the flour, baking powder, salt, pepper, & cayenne. Sprinkle the chilled butter pieces over the top of the flour. Using your fingers or a pastry cutter, rub the butter into the flour mixture until it resembles coarse crumbs. (I used my Ninja Kitchen System on the dough setting, but you can use a food processor too & pulse until desired texture.)
Stir in Parmesan cheese. Add the cream (or milk) & stir until just combined. Crumble the mixture into irregularly shaped pieces onto a baking sheet lined with parchment/wax paper (I actually find it easiest to use scissors & cut off chunks.) Bake the crumble topping until fragrant & starting to brown, about 15 minutes, tossing halfway through. Set aside.
For the filling, heat the olive oil in the now-empty pot over medium heat. Add onion, carrots, celery, a little salt & pepper. Cover & cook, stirring occasionally, until just tender, about 5 minutes. While the vegetables are cooking, shred/cube the chicken into small bite-size pieces. Transfer the cooked vegetables to the bowl with the chicken; set aside.
Over medium heat melt butter in the empty pot. Stir in the flour & cook for one minute, stirring constantly. Slowly whisk in the reserved chicken broth & milk. Bring to a simmer & stir occasionally until the sauce thickens, about 5 minutes, taking care not to burn the bottom. Add ½ tsp salt & ½ tsp pepper. Remove from the heat & stir in the chicken, vegetables, & peas into the sauce.
Pour the mixture into a greased 9x13 pan. Scatter the crumble topping evenly over the filling. Bake at 400˚F until the topping is well browned, & filling is bubbling, about 15-20 minutes. Let the casserole stand for 10 minutes before serving.