Preheat an oven to 350°F and place the oven rack in the middle of the oven.

Start by cutting the pork tenderloin open by making one cut into the center along the entire length, without cutting all the way through it. This opens the tenderloin with two-rounded sides. Next, turn your knife horizontal to the countertop and cut into one of the rounded sides along the entire length, without cutting all the way through it. Repeat with the other side.

To make the filling: Place a large skillet over a medium-high heat and add 1 tablespoon olive oil. When the oil just starts to shimmer, add the minced shallots and sauté slightly until translucent, about 3 minutes. Add pine nuts, olives and spinach. Cook until the spinach starts to wilt, about 2 minutes. Taste and season with salt and pepper.

To stuff and cook the pork loin: Spoon the mixture down the center of your opened tenderloin, being careful not to overfill. Roll the tenderloin and tie it shut with cotton twine at 2-inch intervals.

Place a sauté pan over a medium-high heat and add oil. When the pan is hot, add the tenderloin and brown on all sides, about 3 to 4 minutes per side.

Transfer the tenderloin to a roasting pan and put into the oven. Roast for 15-20 minutes, or until an inserted digital thermometer reads 165°F.

Remove the cooked tenderloin to a cutting board, and allow rest for 10 minutes before carving.

To serve: Using a sharp slicing knife, cut tenderloin across the grain into ¾-inch thick slices. Divide slices between 4 warmed dinner plates, serve immediately.