Preheat your oven to 400°F (200°C). Slice off the top 1/4 inch of each garlic head to expose the cloves. Drizzle with 1 tablespoon olive oil and sprinkle with a pinch of salt. Wrap each head loosely in aluminum foil and place in a small roasting pan or directly on a baking sheet.

Roast for 30-40 minutes, or until the cloves are very soft and slightly caramelized. Let cool slightly, then squeeze the soft garlic pulp from the skins into a small bowl. Mash with a fork until a smooth paste forms. Set aside.

While the garlic roasts, prepare the pork. Pat the pork loin thoroughly dry with paper towels. In a small bowl, combine smoked paprika, dried thyme, garlic powder, onion powder, 1 tsp salt, and 1/2 tsp black pepper. Rub this spice mixture all over the pork loin.

Heat 1 tablespoon olive oil in a large oven-safe cast iron skillet over medium-high heat. Once hot, sear the pork loin on all sides until deeply golden brown, about 2-3 minutes per side (8-10 minutes total).

Transfer the skillet with the seared pork loin to the preheated oven (alongside the garlic, if still roasting, or after removing it). Roast for 15-20 minutes, or until an internal temperature of 140-145°F (60-63°C) is reached with a meat thermometer in the thickest part. The exact time will depend on the thickness of your pork loin.

Remove the pork from the oven and transfer it to a cutting board. Tent loosely with aluminum foil and let rest for at least 10 minutes. This is crucial for juicy pork; the temperature will rise to 145-150°F (63-65°C) during resting.

While the pork rests, prepare the sauce. Return the same skillet (with any pan drippings) to medium heat. Add 2 tablespoons unsalted butter. Once melted, add the minced shallot and cook for 2-3 minutes until softened and fragrant.

Pour in the dry white wine (if using) and deglaze the pan, scraping up any browned bits from the bottom. Let it simmer for 1-2 minutes until slightly reduced. Stir in the chicken broth and bring to a simmer, reducing slightly for 3-4 minutes.

Whisk in the mashed roasted garlic and heavy cream. Bring the sauce to a gentle simmer and cook, stirring occasionally, for 5-7 minutes, until it thickens to your desired consistency. Stir in the grated Parmesan cheese and Dijon mustard.

Season the sauce with salt and black pepper to taste. If the sauce is too thick, thin it with a splash of chicken broth or water. If it's too thin, simmer a few more minutes.

Slice the rested pork loin into thick medallions. Arrange on a platter or individual plates. Spoon a generous amount of the roasted garlic cream sauce over the pork. Garnish with fresh chopped parsley and serve immediately.