Remove steaks from refrigerator and let sit at room temperature for 30 minutes before cooking. Preheat your grill to medium-high heat, around 400°F. Let it heat for at least 10 minutes to ensure even, consistent heat across the surface.

Pat the ribeye steaks completely dry with paper towels. Rub both sides evenly with olive oil, then season generously with minced garlic, chopped rosemary, salt, and pepper. Press the seasonings gently into the meat so they adhere during grilling.

Place the steaks on the preheated grill and cook for 4 to 5 minutes on the first side without moving them to create a golden-brown crust. Flip once and cook for another 4 to 5 minutes for medium-rare (internal temperature of 130°F). For medium, add 1 to 2 minutes per side.

While the steaks finish grilling, prepare the wine sauce. Pour the red wine into a separate pan over medium-high heat and bring to a boil. Reduce heat to medium and simmer until reduced by half, about 8 to 10 minutes. The sauce should coat the back of a spoon.

Remove the steaks from the grill when they reach your desired temperature and transfer to a cutting board or plate. Let them rest for 5 minutes to allow juices to redistribute throughout the meat.

Turn the heat under your wine sauce to low and whisk in the cold butter until fully melted and incorporated. The sauce should look glossy and silky. Season with a pinch of salt if needed.

Plate the rested steaks and drizzle generously with the red wine sauce. Garnish with fresh parsley and serve immediately with your choice of sides.