Preheat oven to 400. Place the shredded chicken in a greased 9x13 casserole dish.
Heat the butter and olive oil in a large skillet over medium heat until hot.
Add the leeks and cook until softened. Next, add the mushrooms and cook until tender.
Spoon the mushroom leek mixture on top of the chicken. (If there is liquid from the mushrooms, leave it in the skillet).
Add the broth, cream cheese, sour cream, salt, and pepper to the skillet. Stir until smooth. It helps to puree with an immersion blender at this point.
Pour the sauce over the filling in the casserole dish.
Stir together the pork rind crumbs and butter. Sprinkle over the casserole.
Bake for 20-25 minutes or until hot and bubbly.
Notes
Topping: If you don't need this to be gluten-free, you can swap in panko breadcrumbs.To Store: Keep in an airtight container in the fridge for up to 4 days. To Reheat: Place on a microwave-safe dish and heat for 1-3 minutes or until hot.