French Dip Panini

I got this recipe from Rachael Ray....it makes my mouth water everytime I see the recipe in my book. So simple yet SO GOOD. I could just drink the dipping sauce, it's so tasty! Very few, easily found ingredients and my kids AND husband devour them so it's a big hit all around.

French Dip Panini
4 Tbsp butter, softened
1 shallot, finely chopped
1 Tbsp cornstarch
2 cups beef broth
1 pound sliced roast beef (from the deli)
1 baguette, split lengthwise and sliced crosswise into 4 sections
4 ounces sliced cheese of your choice (cheddar, pepper jack, swiss, whatever you like)

In a deep skillet, melt 2 Tbsp butter over medium heat. Add the shallot and cook, stirring until translucent, 1 to 2 minutes. Whisk in the cornstarch, cook for 1 minute. Whisk in beef broth. Add the roast beef to the sauce and warm over low heat. Preheat a nonstick grill pan or griddle over medium heat. Spread the remaining 2 Tbsp butter on the split sides of the baguette sections. Using tongs, top half the sections with the warm roast beef, reserving the sauce. Top with the cheese (add other fillings if desired, see below) and remaining baguette sections. Place the panini on the hot pan. Weigh down with a heavy skillet or panini press and cook for 2 minutes, then flip the panini and cook 2 minutes longer. Remove the panini from the heat and divide the sauce (make sure it's still hot) among 4 small bowls for dipping.
**We also love to add thinly sliced red onion and sometimes a little bit of horseradish to the panini, just to give them a little kick.