Braised Lamb Shanks

Arrange a rack in center of oven; preheat to 350°. Season lamb shanks with salt and pepper. In a large Dutch oven over medium-high heat, heat oil. Working in batches if needed, add lamb and cook until golden brown all over, about 4 minutes per side. Transfer lamb to a plate.

In same pot over medium heat, melt 2 Tbsp. butter. Add onion and carrots and cook, stirring occasionally, until softened, about 7 minutes. Add garlic and cook, stirring, until fragrant, about 1 minute more. Add tomato paste and cook, stirring, until vegetables are coated, about 2 minutes.

Pour in broth and tomato sauce, then return lamb shanks to pot. Add rosemary and bring to a boil. Cover and transfer to oven.

Braise until lamb shanks are completely tender, about 2 hours.

Transfer lamb to a cutting board. Tent with foil to keep warm. Discard rosemary.

Return pot to stove over medium heat. Add wine and bring to a boil. Reduce heat to medium-low and bring to a simmer. Cook, stirring occasionally, until thickened, about 10 minutes. Stir in remaining 2 Tbsp. butter.

Serve lamb with mashed potatoes (if using) and spoon sauce on top.