Panera Bread Roast Beef and Smoked Gouda Pannini

We recently got a Panera Bread in our neck of the woods and I love it!  I have been on their website looking for recipes that I love.  I hadn't tried this one, but my husband loves smoked gouda so I though it was worth a try.  Here is the recipe directly from their website:

Ingredients

• ¼ cup light mayonnaise
  
• 1 tablespoon prepared horseradish
  
• 1 tablespoon minced red onion
  
• 8 thin slices Panera Bread Sourdough Loaf
  
• 8 thin slices (about 12 ounces) rare roast beef
  
• ¼ cup A.1. steak sauce
  
• 1½ cups (1½ ounces) baby arugula leaves
  
• 2 cups (8 ounces) grated smoked Gouda
  

Directions

1. Warm a panini press or heavy skillet over medium-high heat.
2. Combine the mayonnaise, horseradish, and onion, and spread the mixture over the bread.
3. Drizzle each slice of beef with a little steak sauce, distributing it evenly. Place two slices of beef onto each of 4 bread slices, and top with evenly divided amounts of arugula and cheese. Add the remaining bread slices, compressing the sandwiches slightly.
4. Coat the outside of the sandwiches with cooking spray, and heat them in a panini press—or skillet under a heavy weight (such as another skillet)—until they are browned and the cheese melts, 3 to 4 minutes per side.