1. Preheat the oven to 375 degrees F. Sprinkle the pork with salt and pepper. Heat a large, ovenproof skillet over medium-high heat. Add the oil; add the pork and cook, turning occasionally, until browned on all sides. Transfer the pork to a cutting board.

2. Return the skillet to medium heat. Add the butter, thyme, parsley, rosemary, and garlic; cook, stirring, until fragrant, about 1 minute. Stir in the panko and 1 teaspoon salt; cook, stirring, until the panko is golden, about 2 minutes. Transfer the toasted breadcrumbs to a piece of wax or parchment paper.

3. Brush the pork with 2 tablespoons of the mustard and roll in the toasted breadcrumbs to coat. Return the coated pork to the skillet. Halve the garlic heads crosswise and add to the skillet. Roast until an instant-read thermometer inserted into the center of the pork registers 145 degrees F, about 45 minutes. Transfer the pork and garlic to a cutting board and let rest 10 minutes.

4. Meanwhile, place the skillet over medium-low heat. Add the honey, remaining 1/3 cup mustard, and 1/4 cup water and stir until combined. Simmer until the mixture is slightly thickened, about 2 minutes. Slice the pork and serve with the roasted garlic and the mustard sauce.