Instructions

  1. Combine ground beef, salt, and pepper in a large bowl; mix well, and shape into 16 thin patties. It easier to form 8 equally portioned balls of meat, then halve it to form the patties.
  2. Combine cream cheese, blue cheese, onion, horseradish, and mustard in a small bowl; beat at medium speed of an electric mixer until blended. Divide cheese mixture evenly among 8 patties; spread to within 1/2 inch of edges. Top with the remaining patties, pressing edges to seal. Make sure to seal them well.
  3. Grill hamburgers over medium-hot coals (350 to 400 degrees) 10 minutes on each side or to desired degree of doneness. Set aside, and keep warm.
  4. Saute mushrooms in melted butter in a skillet until tender. Top burgers with sauteed mushrooms.