Heat grill to medium-high heat.
Mix meat and 3 Tbsp. Our Favorite Chimichurri just until blended; shape into 6 (1/2-inch-thick) patties.
Grill 5 to 6 min. on each side or until done (160°F). Top with Singles; grill 1 min. or until melted.
Fill buns with cheeseburgers and remaining chimichurri.