* Spread 1 side of each bread slice with butter.
* Place 4 bread slices, butter sides down, in large skillet or on grill pan.
* Top with beef, pesto and cheese.
* Top with remaining bread slices, butter sides up.
* Cook over medium heat 4 to 5 minutes, turning once, until bread is crisp and cheese is melted.
* Serve with pasta sauce.