In small bowl, mix salsa and pasta sauce; set aside.
Set oven control to broil. Lightly spread one side of each bread slice with 1/2 teaspoon butter. On ungreased cookie sheet, place half of bread slices, buttered side down. Top each with a slice of cheese. Cover with remaining bread slices, buttered side up.
Broil 3 to 4 minutes, turning once, until golden brown and cheese is melted. Serve sandwiches with salsa mixture.