Stuffed Border Burgers

Ingredients
1 1/2 pounds lean ground beef
1/2 cup finely chopped onion
1 (4.25-ounce) can chopped ripe olives, drained
2 tablespoons ketchup
1 teaspoon chili powder
1 teaspoon fajita seasoning
6 (1-ounce) slices Monterey Jack cheese with peppers
6 onion rolls, split and toasted

Combine first 6 ingredients. Shape mixture into 12 (4-inch) patties. Fold cheese slices into quarters; place cheese on each of 6 patties. Top with remaining 6 patties, pressing to seal edges.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 4 to 5 minutes on each side or until done. Serve on rolls with Tex-Mex Secret Sauce and desired toppings.