In a large pot, boil the breasts until tender and they fall off the bone. Remove and cool.
When meat has cooled, remove meat from the bones and cut into 1" cubes.
In a large skillet, melt the butter. Add the onion and lightly sauté.
Add the pheasant and season to taste with salt and pepper. Add the Cajun seasoning.
Cook until the meat is lightly browned.
Pour the meat mixture into a baking dish.
Mix the soup, wine, broth and mushrooms together in a bowl. Pour over the meat.
Cover and bake at 350 degrees for 30 minutes.
Serve with mashed potatoes and enjoy.