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

In a large skillet, heat olive oil over medium-high heat. Once hot, add the ribeye steaks and sear for about 4-5 minutes on each side until a nice crust forms. Remove the steaks from the skillet and set aside.

In the same skillet, add minced garlic and chopped rosemary. Sauté for about 1 minute until fragrant.

Pour in the balsamic vinegar, scraping up any browned bits from the bottom of the skillet. Allow the vinegar to reduce for about 3-4 minutes.

Add the beef broth to the skillet and return the ribeye steaks to the pan. Bring to a simmer, cover, and reduce the heat to low. Cook for about 30-40 minutes until the steaks are tender and cooked to your desired doneness.

While the steaks are braising, in a separate pot, melt 2 tablespoons of butter over medium heat. Add the diced carrots, parsnips, and potato. Sauté for about 5-7 minutes until they begin to soften.

Add the sliced leeks and dried marjoram, cooking for another 5 minutes until the vegetables are tender.

Once the vegetables are cooked, add a splash of the braising liquid from the skillet to the pot and stir. Using an immersion blender or a regular blender, blend the mixture until smooth. If it's too thick, add more of the braising liquid to reach your desired consistency.

Once the steaks are done braising, remove them from the skillet and let them rest for a few minutes. Strain the remaining braising liquid if desired, then return it to the heat to thicken further if necessary.

Serve the ribeye steaks on plates, topped with the balsamic glaze and accompanied by the velvety root vegetable gravy. Garnish with fresh parsley if desired.