Preparation

Make the stuffing

• Position a rack in the center of the oven and heat to 350°F. Arrange the bread in a single layer on a large rimmed baking sheet and toast until crisp, about 15 minutes. Cool to room temperature.
• In a small bowl, combine the bourbon with 2 Tbs. water. Add the apricots and soak until soft, about 20 minutes. Strain the apricots over a bowl, squeezing them to extract more liquid. Reserve any liquid—it won’t be much—to add to the glaze, and set the apricots aside.
• Heat the oil in a large skillet over medium heat. Add the onion and celery, and cook, stirring occasionally and adjusting the heat as necessary, until very soft but not browned, about 8 minutes. Transfer to a large bowl. Add the bread, apricots, parsley, sage, thyme, mustard, 1 tsp. salt, 1/4 tsp. pepper, and the cayenne.
• In a small bowl, whisk the broth and eggs, and pour over the bread mixture. Toss well, let sit for 5 minutes, and toss again. cover and chill for at least 30 minutes and up to 1 day.

Wrap the pork

• Pat the pork tenderloin dry and season well with salt and pepper.
• Lay some plastic wrap on a work surface so that it measures at least 20×20 inches; overlap a couple of pieces of plastic wrap as needed. Shingle 2 rows of prosciutto, using 6 to 8 slices for each row to make a 14×14-inch square. Spoon the stuffing mixture onto the prosciutto, then use your hands to lightly press it into an even layer, leaving a 1-1/2-inch border on top and bottom and a 1-inch border on each side. Position the pork across the center of the stuffing.
• Lift the plastic to help wrap the prosciutto and stuffing around the pork, and continue to roll up like a sushi roll, encasing the pork with the stuffing and prosciutto. Tuck in the ends of the prosciutto, then wrap the roll tightly in the plastic wrap, twisting the ends to tightly compress the roast. Tuck the ends under the roast to keep snug. Chill for at least 30 minutes and up to 1 day. Longer is better as it helps the stuffing to firm up.

Roast and glaze the pork

• Position a rack in the center of the oven and heat to 375°F. Set a rack in a roasting pan lined with parchment.
• In a small saucepan, combine the reserved apricot soaking liquid with the brown sugar and mustard over medium heat. Simmer, stirring occasionally, until smooth, about 2 minutes. Add the cayenne, and season to taste with salt and pepper. if too thick to brush easily, thin with a little water.
• Remove the plastic wrap from the pork and place the pork seam side down in the center of the rack. Roast, brushing the prosciutto with the glaze during the last 10 minutes of cooking, until cooked (135°F), 55 to 65 minutes. Let rest for 15 minutes, then slice the roast with a very sharp knife into thick slices.