1 cup butter, softened
7 cloves garlic, minced
2 tablespoons fresh rosemary, finely chopped
2 tablespoons fresh thyme, finely chopped
2 tablespoons salt
1 tablespoon pepper
5-7 pounds boneless ribeye roast, trimmed
2 tablespoons flour
2 cups beef stock
Step 1: Preheat oven to 500°F/260°C.
Step 2: Mix together the butter, garlic, herbs, salt, and pepper in a bowl until evenly combined.
Step 3: Rub the herb butter all over the rib roast, then place on a roasting tray with a rack.
Step 4: Bake for 5 minutes per pound of meat — so a 5-pound roast would bake for 25 minutes and a 7-pound roast would bake for 35 minutes.
Step 5: Turn off the heat and let the rib roast sit in the oven for 2 hours, making sure you do not open the oven door or else the residual heat will escape.
Step 6: Once the 2 hours are up, remove the roast from the pan and pour the pan drippings into a saucepan over medium heat.
Step 7: Add the flour, whisking until there are no lumps, then add the beef stock, stirring and bringing the sauce to a boil.
Step 8: Remove from heat and strain the sauce into a gravy dish.
Step 9: Carve the prime rib into ¾-inch slices, then serve with the mashed potatoes and sauce!