Preparation

Make the stuffing:

• Melt the butter in a 10-inch skillet over medium heat. Add the onion and cook, stirring frequently, until soft and lightly browned, about 4 minutes. Set aside to cool. Put the dates and apricots in the bowl of a food processor and pulse until finely chopped. Add the hazelnuts, parsley, sage, and reserved onions and pulse a few more times until everything is minced and well combined. Transfer to a small bowl and season to taste with salt and pepper.

Prepare the turkey breast:

• Heat the oven to 350ºF. Put the turkey breast on a cutting board and, holding your knife parallel to the work surface, slice open the turkey breast horizontally, working from the thicker side of the lobe to the thinner side and not cutting all the way through.
• Open the turkey breast like a book and season generously with salt and pepper. Spread the stuffing evenly over half the opened turkey breast, leaving a little border around the outer edges. Fold the other half of the turkey breast over the stuffing, enclosing the stuffing as much as possible.
  
• Lay the bacon lengthwise on top of the turkey breast and tie the breast crosswise with kitchen string in four or five places to hold it all together.
• Season the turkey on both sides with salt and pepper. Heat the oil in a 12-inch ovenproof skillet over medium-high heat. Beginning with the bacon side down, sear the turkey breast on both sides until nicely browned, 3 to 4 minutes per side. Transfer the skillet to the oven (the turkey should be bacon side up) and roast for 20 minutes. Remove the pan from the oven, flip the turkey breast, return to the oven, and roast until an instant-read thermometer inserted into the center of the breast reads 165ºF, 20 to 30 minutes more.
• Remove the pan from the oven, transfer the turkey to a large plate and let it rest, loosely covered with foil, for about 10 minutes.

Make the marsala glaze

• Pour off the fat from the skillet and discard any lumps of stuffing that may  have fallen out of the turkey and burned. Put the skillet over medium-high heat, pour the Marsala in the skillet, and bring it to a boil, stirring with a wooden spatula to scrape up any browned bits on the bottom of the pan. Add to the pan any juices that have collected around the turkey while resting on the plate. Continue boiling until the Marsala is reduced to 1/4 cup, 5 to 7 minutes. Season with salt and pepper to taste.
• Remove the strings from the turkey. Slice the turkey crosswise into 1/2-inch slices and arrange the slices on a serving platter. Pour the Marsala glaze into a small bowl and pass with the turkey.