Tomahawk Steak Sandwich

Ingredients

• 1 beef Tomahawk Steak , about 2-1/2 pounds
• Salt and pepper, to taste
• 2 tablespoons olive oil
• 2 cloves garlic, minced
• 2 tablespoons butter, softened
• 1 tablespoon finely chopped fresh rosemary
• 4 ciabatta rolls, split and toasted
• 1/4 cup mayonnaise
• 2 cups arugula
• 1 small red onion, thinly sliced
• 1/4 cup horseradish sauce
• Blue cheese crumbles or provolone slices (optional)