This rich and savory main dish serves a crowd and is perfect for holiday gatherings.
Heat oven to 400 degrees. Remove papery outer skin from garlic head. Place garlic head on square of foil; drizzle with 1 tablespoon olive oil, and wrap. Bake until softened, about 45 minutes. When cool enough to handle, squeeze garlic flesh from head, pressing garlic against work surface with flat side of table knife.
Arrange 3 tenderloins on work surface, flat side up. Spread flat side of each tenderloin with one-third of the roasted garlic. Strip leaves from fresh sage, rosemary, and thyme; discard stems. Place one-third of each herb on each tenderloin, scattering leaves over the garlic. Place 3 remaining tenderloins on top of herb-coated tenderloins, with the flat sides down, and matching the larger ends to the tapered ends. Wrap 6 strips of bacon around each pair of tenderloins; tie bacon in place with kitchen twine. Sprinkle with salt and pepper on all sides.
Place large, heavy-bottomed skillet over high heat. Add remaining tablespoon oil and butter, and melt. Arrange tenderloins in skillet in batches to keep them from touching. Sear until golden brown on all sides, rotating as needed, about 10 minutes per tenderloin. Transfer seared tenderloins to large roasting pan; place in the oven. Roast until meat thermometer inserted into thickest part of meat registers 150 degrees. about 15 minutes. Transfer tenderloins to cutting board; let stand 10 minutes. Remove twine before carving.
Pork tenderloins can be prepared in advance and cooked shortly before serving. Tying two tenderloins together ensures even cooking.