Preheat the oven to 325°F (163°C).

Season the lamb shoulder generously with salt and black pepper, ensuring it's evenly coated.

In a large oven-safe pot or Dutch oven, heat the olive oil over medium-high heat. Once hot, sear the lamb shoulder on all sides until golden brown, about 4-5 minutes per side. Remove the lamb from the pot and set it aside.

In the same pot, add the halved spring garlic and sauté for 2-3 minutes until charred and fragrant.

Add the wild marjoram and stir for another minute to release its aroma.

Return the lamb shoulder to the pot and pour in the chicken or lamb stock. Bring the mixture to a simmer.

Cover the pot with a lid and transfer it to the preheated oven. Braise for 2-3 hours, or until the lamb is fork-tender and easily pulls away from the bone.

While the lamb is braising, prepare the turnip pan gravy. In a separate pot, combine the turnip cubes with enough water to cover them. Bring to a boil and cook until tender, about 15-20 minutes. Drain and set aside.

Once the lamb is done, remove it from the pot and set it aside to rest. Strain the braising liquid into a saucepan, discarding solids.

In the same saucepan, melt the butter over medium heat. Whisk in the flour to create a roux, cooking for 2-3 minutes until golden.

Gradually add the strained braising liquid to the roux, whisking continuously to prevent lumps. Bring to a simmer and cook until thickened.

Stir in the heavy cream and the reserved turnips. Cook for an additional 5 minutes, season with salt and pepper to taste.

Slice the lamb shoulder and serve it with the velvety turnip pan gravy drizzled over the top.