Step 1

Adjust oven rack to middle position and heat oven to 300 degrees. Combine panko; 2 tablespoons oil; thyme; garlic; anchovies, if using; 2 teaspoons salt; and 1 teaspoon pepper in 12-inch nonstick skillet. Cook over medium heat, stirring frequently and breaking up any clumps, until golden brown, about 5 minutes. Transfer to shallow dish. Stir in parsley and lemon zest.

Step 2

Wipe skillet clean with paper towels. Set wire rack in rimmed baking sheet. Pat lamb dry with paper towels, sprinkle each rack with 1 teaspoon salt, and season with pepper. Heat remaining 1 teaspoon oil in now-empty skillet over medium-high heat until just smoking. Place 1 rack in skillet and cook until well browned, 2 to 4 minutes per side, using tongs as necessary to stand up rack to brown loin portion. Transfer to prepared wire rack. Pour off all but 1 teaspoon fat from skillet and repeat cooking with remaining rack of lamb. Let lamb cool for 5 minutes.

Step 3

Brush lamb all over with mustard. Working with 1 rack at a time, transfer lamb to panko mixture, turning to coat all sides and pressing gently to adhere. Return lamb to wire rack, fat side up. Roast until lamb registers 135 degrees for medium, 40 to 50 minutes. Transfer to carving board and let rest for 15 minutes. Cut between bones to separate chops. Serve.