Step 1

Season roast all over with salt and pepper (use about 1 tsp. Diamond Crystal kosher salt or ½ tsp. Morton kosher salt per pound; this guideline is especially important with large cuts of meat). Place roast on a wire rack set inside a large rimmed baking sheet (this setup will keep the meat from sitting directly in the liquid that will get drawn out by the salt, allowing it to cook more evenly later). Let sit at room temperature at least 2 hours, or cover and chill up to 2 days. If you’re chilling the meat, move it back to the counter and let it sit at room temperature for the final 2 hours. Taking the chill off of the roast before it goes into the oven means it will cook in less time.

Step 2

Meanwhile, finely chop 10 anchovies and 2 rosemary sprigs. Transfer to a small bowl and add garlic and olive oil. Mix well to combine and season with salt and pepper.

Step 3

Preheat oven to 250°. Scatter remaining 4 rosemary sprigs across another rimmed baking sheet. Place meat on top and smear anchovy mixture all over. Roast until an instant-read thermometer inserted into the thickest part registers 110° for medium-rare, 2–2½ hours (temperature will rise as it sits; it should eventually hit 125°). Let rest at least 30 minutes.

Step 4

About 20 minutes before you want to sit down to eat, increase oven temperature to 500°. Roast meat on the same baking sheet until fat is golden brown, 10–15 minutes. Transfer roast to a cutting board, leaving any pan juices behind. Remove rosemary sprigs from baking sheet; discard. Add ¾ cup parsley to juices and stir to coat. Transfer to a small bowl.

Step 5

Slice roast away from bones (you can separate bones and crisp up in the oven or serve them as they are). Slice meat to your preferred thickness. Arrange on a platter and pour parsley mixture over. Sprinkle with sea salt and more parsley. Serve with more anchovies alongside if desired.

Step 6

Do Ahead: Meat can be roasted 2 hours ahead. Store loosely covered with foil at room temperature.