Pat lamb shanks dry and season generously with salt and pepper.

Heat olive oil in a large skillet over medium-high heat. Brown the shanks on all sides until deeply colored (about 3–4 minutes per side). Work in batches if needed.

Transfer the browned shanks to your slow cooker and set aside.

In the same skillet, lower heat to medium and add smashed garlic. Sauté for 30–45 seconds until fragrant — don’t let it burn.

Pour in the red wine and scrape the browned bits from the skillet with a wooden spoon. Let the wine reduce for 1–2 minutes.

Add the beef broth to the skillet, stir, then pour the whole mixture over the lamb shanks in the slow cooker.

Tuck in the rosemary and thyme sprigs, cover, and cook on low for 6–8 hours until the shanks are tender and the meat pulls away from the bone.

About 1 hour before serving, add the cubed potatoes to the slow cooker so they cook through but hold their shape.

When done, remove the shanks and potatoes to a serving dish. Skim any excess fat from the sauce, then stir 2 tbsp butter into the remaining sauce in the slow cooker for shine and flavor.

Spoon the sauce over the shanks and potatoes and serve.