Heat oven to 400° F; butter shallow baking dish and sheet of foil.
Spread out cornbread on baking sheet and toast till golden brown, 10-15 minutes. Let cool.
Place in large mixing bowl.
Reduce oven temperature to 350° F.
Meanwhile, heat large skillet sprayed with oil; cook sausage, stirring and breaking up into small pieces, until brown. Transfer to bowl with slotted spoon. Add onion and fennel to skillet, season with salt and pepper. Cook, stirring often, until onions are golden brown and soft, 10-12 minutes. Add garlic and sage, stirring about 2 minutes. Transfer to bowl with cornbread.
Reduce skillet heat, add cherries with a little broth to skillet, scraping up any brown bits. Add butter; cook, stirring until melted. Add to bowl.
Whisk egg with 1 cup chicken stock; pour over cornbread mixture. Add parsley, season with salt and pepper. Gently toss mixture, adding enough chicken stock to hydrate. (Be gentle so cornbread doesn’t break up.) Transfer to baking dish and dot with a little butter (if desired).
Cover with buttered foil; bake until a paring knife inserted into the center comes out hot, 30-35 minutes. Increase oven temperature to 450° F. Uncover and bake until top is golden brown and crisp, 20-25 minutes. Let sit for 10 minutes before serving.