Heat the oven to 375º

If necessary, trim the lamb of most of the fat, but do leave a thin layer to keep the meat moist.

Finely chop the bread in a food processor. Add the garlic, parsley, mint, and thyme and pulse to finely chop. Add the butter, 1/2 teaspoon salt and 1/8 teaspoon of pepper. Pulse until mixture just comes together.

Place racks, fat-side up, in a large baking dish (you may need to do one rack per dish) or on a heavy-duty, sided baking sheet. Season with salt and pepper. Divide the butter mixture in half and press butter mixture evenly over the top (fat-side) of the racks.

Roast racks 25 minutes, then tent loosely with foil and roast until thermometer inserted diagonally into the thickest part of meat registers 135º for medium-rare, about 10 minutes more. Transfer to cutting board and let stand 10 minutes. Cut racks into chops and serve.