Heat a large grill pan over medium-high heat. Add 4 bread slices; cook 2 minutes on each side or until lightly browned. Remove from pan. Repeat procedure with remaining bread slices. Rub 1 side of each bread slice with cut sides of garlic clove; discard garlic.
Combine cheese and remaining ingredients, stirring well. Spread about 3 tablespoons cheese mixture over the garlic side of each of 4 bread slices; top each sandwich with 1 bread slice, garlic side down.