Pat dry and prep the pork. Blot the pork loin with paper towels so it browns better and holds seasoning. Trim any large surface silverskin, but keep a thin fat cap if present.
Mix the garlic butter rub. In a small bowl, combine softened butter, minced garlic, smoked paprika, onion powder, thyme, rosemary, salt, and pepper. Stir until it forms a paste.
Season the meat. Rub the garlic-butter mixture all over the pork loin, coating the top, bottom, and sides.
Get it into any creases for even flavor.
Brown for extra flavor (optional but recommended). Heat olive oil in a large skillet over medium-high. Sear the pork loin on all sides, 2–3 minutes per side, until nicely browned. Transfer to the crockpot.
Wrap with bacon. Lay bacon strips over the pork loin, slightly overlapping, tucking the ends under the roast if needed.
The bacon will baste the meat as it cooks.
Add liquid and mustard. Pour chicken broth into the crockpot around the pork (not on top so the bacon stays put). Whisk Dijon into the broth if using.
Slow cook. Cover and cook on Low for 4.5–6 hours or on High for 2.5–3.5 hours, until the internal temperature reaches 145°F (63°C) at the thickest point.
Rest the roast. Transfer the pork to a cutting board and rest for 10 minutes. This helps the juices redistribute and keeps slices tender.
Crisp the bacon (optional). For extra-crispy bacon, slide the pork under the broiler for 2–3 minutes, watching closely to avoid burning.
Make a quick pan sauce. Skim excess fat from the crockpot juices.
Taste and adjust seasoning. If you want it richer, whisk in a cold pat of butter. For a thicker sauce, simmer in a small saucepan for a few minutes.
Slice and serve. Cut the pork loin into 1/2-inch slices.
Spoon warm garlic-bacon pan sauce over the top and sprinkle with fresh parsley.