1- Ingredients

   1. 1/4 cup shredded Cheddar cheese
   2. 1/4 cup shredded Gruyere cheese
   3. 1 pound 90%-lean ground beef
   4. 1 tablespoon Worcestershire sauce
   5. 1 1/2 teaspoons paprika
   6. 1/4 teaspoon freshly ground pepper

2-  Cooking
 
   1.  Preheat grill to medium-high or preheat the broiler.
   2. Combine Cheddar and Gruyere in a small bowl.
   3. Gently mix beef, Worcestershire, paprika and pepper in a large bowl, preferably with your hands, without overworking. Shape into 8 thin, 4-inch-wide patties. Mound 2 tablespoons of the cheese mixture on each of 4 patties, leaving a 1/2-inch border. Cover each with one of the remaining patties. Crimp and seal the edges closed.
   4. To grill: Lightly oil the grill rack (see Tip). Grill the stuffed patties over medium-high heat, about 4 minutes per side for medium-well. (Be sure not to press the burgers as they cook or they'll split open and the cheese will ooze out.) To broil: Cover a broiler pan with foil and coat with cooking spray. Broil the stuffed patties in the upper third of the oven, about 4 minutes per side for medium-well. In either case, let the burgers stand for 5 minutes before serving.

3-Why put the cheese on top of the burger when half of it just melts off--Instead, form the burger around the cheese so you can char the meat and safeguard the more delicate flavors. Use any mixture of hard or semihard cheeses-Emmentaler and Gouda or Asiago and Parmigiano-Reggiano also pair well.

Notes: Tip  To oil a grill rack: Oil a folded paper towel, hold it with tongs and rub it over the rack. (Do not use cooking spray on a hot grill.)

From ; yahoo