Prep the oven and pan: Heat the oven to 450°F (230°C). Line a sheet pan with foil and set a wire rack on top for airflow. Pat the lamb dry with paper towels.

Season the lamb: Sprinkle the racks all over with salt and pepper. Let sit at room temperature for 20–30 minutes. This helps even cooking.

Make the herb crust: In a bowl, combine breadcrumbs, garlic, rosemary, thyme, parsley, lemon zest, melted butter, and 1 tablespoon olive oil. Season with a pinch of salt and pepper. The mixture should be damp, not soggy.

Sear the racks: Heat a large skillet over medium-high. Add 1 tablespoon olive oil. Sear the lamb, fat side down first, until nicely browned, about 2–3 minutes per side. Transfer to the prepared rack, fat side up. Let cool 2–3 minutes so the mustard doesn’t slide off.

Mustard coat: Brush the top and sides with Dijon (mix in grainy mustard if using). Apply a thin, even layer—this is the glue for the crust.

Crust it: Press the breadcrumb-herb mixture onto the mustard-coated surfaces, packing gently so it adheres. Some crumbs may fall; that’s fine.

Roast: Place the racks in the oven and roast for 15–18 minutes for medium-rare (about 125–130°F/52–54°C at the center when pulled). For medium, roast 18–22 minutes (130–135°F/54–57°C). Use an instant-read thermometer for accuracy.

Rest: Transfer the racks to a cutting board and rest for 10 minutes. The temperature will rise 5°F as it rests, and the juices will redistribute.

Slice and finish: Cut between the bones into individual chops or double chops. Sprinkle with a little flaky salt and a squeeze of lemon if you like.

Serve: Pair with roasted potatoes, sautéed green beans, or a simple arugula salad. A spoonful of pan juices or a quick pan sauce is a nice touch.