Temper the roast and preheat the oven

• Let the ribeye roast sit at room temperature.
• Preheat the oven to 500 °C.

Make the compound butter

• Place the softened butter in a food processor with the garlic cloves and the chopped rosemary, thyme and oregano.
• Blend until smooth and combined.

Season and coat the roast

• Season the roast with salt and black pepper on all sides.
• Coat the entire roast with the compound butter.

Prepare the roasting pan

• Halve the yellow onions and place them in the middle of the roasting pan to hold the roast above the broth.
• Add the celery, carrots, green onions, leftover herbs and the garlic heads with the tops cut off.
• Pour in the beef broth and set the roast on the onions.

Roast the beef

• Bake at 500 °C for 5 minutes per pound.
• Turn off the oven and leave the roast inside without opening the door.

Caramelize the onions

• Heat the butter and a generous pour of olive oil in a large skillet over medium heat.
• Add the sliced red and yellow onions and cook down.
• Add dashes of Worcestershire sauce, a splash of red wine and season with salt and pepper.

Rest the beef and make the au jus

• Remove the roast from the oven and rest it on a cutting board.
• Set the roasting pan on the stovetop, add the remaining beef broth and simmer.
• Strain the jus.

Make the horseradish sauce

• Squeeze the roasted garlic from the heads into a bowl and purée.
• Stir in the mayonnaise, prepared horseradish, a splash of Worcestershire sauce, salt and pepper.
• Chill in the fridge.

Assemble and broil

• Toast the bread and spread with horseradish sauce.
• Layer with sliced beef, caramelized onions and provolone cheese.
• Broil open-face for a couple of minutes and serve with the au jus.