Preheat oven to 350 degrees and fit a parchment lined baking sheet with a wire rack.
In a heavy bottom sauce pan or dutch oven, melt 3 tablespoons butter. Add diced onion and celery and cook until translucent, about 5 minutes.
Add in sausage, and break up any large chunks. Cook for another 7-10 minutes or so until sausage is cooked through.
Remove from heat and stir in stuffing mix, broth, parsley and sage. Cover and let sit while you prepare turkey breast.
If necessary, butterfly the turkey breast on a cutting board. Cover with a sheet of plastic wrap and then carefully pound out to about ⅓ inch thickness, skin side down if your breast has skin.
Spoon stuffing onto the flattened turkey breast and spread it around, leaving about a ½ inch border on all sides. Make the layer no more than about ½ an inch thick. If you have any left over, add it to a baking dish or ramekins to bake and serve on the side.
Starting at one of the short ends, carefully roll up the turkey breast with stuffing like a jelly roll. Make sure to tuck and stuff any filling that comes out of the sides. Keep rolling and finish with the seam side down.
Cut pieces of kitchen twine and tie snugly around the roll every 1-2 inches. Tie one long piece of twine around the length of the roll for extra security.
Transfer to baking sheet fitted with wire rack. Brush with remaining butter and sprinkle with a little bit of salt and some freshly cracked pepper. You don't need to add much salt as the stuffing mix, broth and sausage are salty and add a lot of flavor.
Bake for 90-120 minutes until internal temperature reaches 165. Basting 2-3 times with the remaining melted butter.
Transfer to cutting board, tent with foil and let rest for 15-20 minutes. Cut through twine and carefully remove.
Slice into one inch slices and serve.