6Easy Drop Biscuitsor refrigerated homestyle biscuits or your favorite biscuit recipe; puff pastry cut into rounds or pie crust cut into rounds (see blog post for ideas)
Chopped fresh parsley or thymeoptional
Arrange the chicken breasts in a single layer in the bottom of a 5-quart or larger crock pot. Sprinkle with ¼ teaspoon salt and ¼ teaspoon black pepper.
In a large skillet or Dutch oven, heat the oil over medium. Add the onion, mushrooms, celery, garlic powder, remaining ¾ teaspoon salt, and ¼ teaspoon pepper. Cook until the onions soften and the mushrooms begin to brown, about 6 to 8 minutes. Stir in the thyme and sage. Transfer to the slow cooker.
Add the broth. Cover and cook until chicken is cooked through and reaches 165 degrees F on an instant read thermometer, 1 ½ to 2 ½ hours on high or 3 to 4 hours on low (the time will vary based on your crockpot; check a bit early to avoid overcooking if yours tends to run hot; if it’s a bit slower, don’t be afraid to add more time if the chicken isn’t done). Remove chicken from the slow cooker. Chop or shred and set aside.
Place the milk and butter in a large, microwave-safe liquid measuring cup or mixing bowl. Heat in the microwave until the butter melts (you can also heat the milk and butter in a medium saucepan on the stove). Whisk in the cornstarch, then pour the liquid into the slow cooker. Stir in the chicken. Cover and cook on high for an additional 30 minutes to thicken. Stir in the frozen vegetables (no need to thaw them first). Cover and cook 10 additional minutes to warm through. Taste and adjust the seasoning as desired. I added a pinch more black pepper.
While the pot pie finishes cooking, preheat the oven and bake the biscuits according to the directions (see blog post for tips to use puff pastry or pie crust). To serve, spoon the filling into serving bowls. Top with a hot biscuit and chopped parsley or thyme as desired. Enjoy immediately.
TO STORE: To store chicken pot pie, place the filling an airtight storage container in the refrigerator for up to 4 days. Store the biscuits at room temperature.
TO REHEAT: Gently reheat the leftover filling in a baking dish in the oven at 350 degrees F until warmed through, topping with fresh biscuits. You can also rewarm this dish in this microwave.
TO FREEZE: Place leftover pot pie filling in an airtight freezer-safe storage container in the freezer for up to 3 months.
TO MAKE AHEAD: Chop all your vegetables up to 3 days in advance, and store them in the refrigerator. You can saute the onion and celery mixture up to 1 day in advance, storing it in the refrigerator.