Stuffed Blue Cheese Burgers

• 1 pound ground round
• 1/4 cup (1 ounce) crumbled blue cheese
• 1 teaspoon olive oil
• 1 large sweet onion, thinly sliced and separated into rings
• 2 cups pre-sliced mushrooms
• 1/8 teaspoon salt
• 1/8 teaspoon pepper
• Cooking spray
• 4 (2.4-ounce) Kaiser rolls
• 4 teaspoons creamy mustard blend (such as Dijonnaise)

1. Divide beef into 4 equal portions. Roll each portion into a ball; make a pocket in the side of each ball, and insert 1 tablespoon blue cheese. Roll back into a ball, and flatten into a 3 1/2- inch pattie. Cover and chill.
2. Prepare grill.
3. Heat oil in a large nonstick skillet over medium- high heat. Add onion, and saute 12 to 14 minutes or until golden. Add mushrooms; saute until tender and liquid is absorbed. Add salt and pepper. Set aside, and keep warm.
4. Place patties on grill rack coated with cooking spray; grill, covered, 6 minutes on each side or until done.
5. Place pattie on bottom half of roll; top each with 1/4 cup onion mixture. Spread 1 teaspoon mustard on cut side of remaining roll halves. Cover burgers with roll tops.

ground round, blue cheese, olive oil, sweet onion, mushrooms, salt, pepper, cooking spray, kaiser rolls, creamy mustard blend

Taken from www.myrecipes.com/recipe/stuffed-blue-cheese-burgers (may not work)