Season the ribeye steaks generously with salt and pepper on both sides.

In a large skillet, heat the olive oil over medium-high heat. Add the ribeye steaks and sear for about 3-4 minutes on each side, or until a nice crust forms. Remove the steaks from the skillet and set aside.

In the same skillet, add the sliced leeks and cook until softened, about 5 minutes. Add the minced garlic and cook for an additional minute until fragrant.

Pour in the port wine, scraping the bottom of the skillet to release any browned bits. Bring to a boil and let it reduce by half.

Return the ribeye steaks to the skillet. Add the beef broth and sage leaves. Cover and reduce the heat to low, allowing the steaks to braise for about 30 minutes, or until tender.

While the steaks are braising, place the cubed rutabaga in a pot of salted water and bring to a boil. Cook until tender, about 15-20 minutes. Drain and return to the pot.

In a separate pan, melt the unsalted butter over medium heat until it turns golden brown and has a nutty aroma. Pour the brown butter over the cooked rutabaga.

Add the heavy cream to the rutabaga and use an immersion blender or a food processor to blend until smooth. Season with salt and pepper to taste.

To plate, spoon the rutabaga purée onto plates, top with the braised ribeye, and drizzle with the port reduction sauce. Garnish with fresh sage leaves.