Melt the butter in a skillet over medium heat. Cook the onion and celery for 5-7 minutes until softened, then add the garlic and cook for 30 seconds.

Place the bread cubes in a large bowl. Add the sautéed vegetables, sage, thyme, salt, pepper, and optional cranberries or nuts, then stir in enough warm stock to moisten the bread without making it soggy. Mix in the beaten egg and cool the stuffing before using.

If needed, butterfly the turkey breast by slicing horizontally through the thickest part and opening it like a book. Cover it with plastic wrap and gently pound it to an even 1/2- to 3/4-inch thickness, then season both sides with salt, pepper, sage, and thyme.

Spread the cooled stuffing over the turkey, leaving about a 1-inch border. Roll it tightly from one long side into a roulade, tie it with kitchen twine at 1- to 2-inch intervals, and secure the ends.

Place the roulade seam-side down in a roasting pan. Rub the outside with olive oil or melted butter and pour 1 cup of stock into the bottom of the pan.

Roast uncovered at 375°F (190°C) for approximately 1 hour 15 minutes to 1 hour 40 minutes, depending on the turkey's thickness and weight. Baste once or twice if desired, and cover loosely with foil if the exterior browns too quickly.

Check the thickest part of the turkey and the center of the stuffing with an instant-read thermometer. Both areas must reach 165°F (74°C) before the roulade is removed from the oven.

Transfer the cooked turkey to a cutting board, tent loosely with foil, and rest for 15-20 minutes. Remove the twine and slice into 1/2- to 1-inch rounds before serving.