If challah is fresh, toast challah cubes in the oven for about 15 minutes until they are lightly toasted.
Preheat oven to 350 degrees F.
In a large skillet, drizzle olive oil and break up turkey sausage into small bite size pieces. Allow meat to cook until fully cooked through and then reserve to another plate.
In the same pan, add the leeks, celery and mushrooms and allow everything to cook until leeks begin to wilt and mushrooms begin to soften.
When vegetables begin to soften, add the chopped herbs and season with salt and pepper. Add chicken stock and dried cherries and coat all the vegetables. Cook for additional 2 minutes so the cherries begin to plump up.
In a large baking dish add challah and vegetable mixture together. Toss everything together and add more stock if it feels too dry.
Dot with butter all over the top and bake for about 40 minutes. Garnish with fresh herbs.