For the tenderloin: Begin by placing a large sheet of plastic wrap on a clean bench top (use 2 overlapping sheets if you have to). In the center of the plastic, lay the bacon slices vertically, slightly overlapping one another, working from left to right. Sprinkle the tenderloin with the salt and pepper. Place the beef tenderloin horizontally across the strips of bacon (along the bottom of the rectangle of bacon). Roll up the plastic and bacon around the beef so it is wrapped tightly and evenly. Twist the ends of plastic to tighten and form the meat into an even log shape. Place in the refrigerator to firm up for 1 hour so the bacon sticks to the beef and the roast retains its nice even shape.
Preheat the oven to 375 degrees F.
Set a large cast-iron pan (or roaster) over high heat and coat lightly with canola oil. Remove the beef from the fridge and discard the plastic. Place the roast seam-side down in the pan and brown on all four sides, 4 to 5 minutes per side. When completely browned, place the whole pan in the oven and roast for about 30 minutes (an instant-read thermometer should register 135 degrees F for medium-rare). When done, remove from the oven and transfer the roast to a platter to rest before slicing into 1/2-inch-thick slices.
For the peppercorn sauce: Set the pan used for the beef over medium heat. Discard all but 2 to 3 tablespoons of fat from the pan, and then add the garlic and shallots. Season with some salt and saute until caramelized, 2 to 3 minutes. Then add the green peppercorns. Mix well, and then remove the pan from the heat and carefully add the whiskey (you can flambe if you like here by igniting the alcohol in the pan). Return the pan to the heat and cook down until just about all the liquid has reduced before adding the beef stock and heavy cream. Bring to a simmer and cook to allow flavors to meld, 2 to 3 minutes. Remove from the heat and add the cold butter cubes, swirling as they dissolve. Taste and, if needed, season with more salt. Serve with the slices of bacon wrapped tenderloin.