In a small bowl, add the chimichurri to the chicken and mix until evenly coated.
Butter the outside of each piece of bread with about one teaspoon and place one piece butter side down in the skillet. Top with the chimichurri chicken mixture followed by the cheese and second piece of bread (buttered side out).
Cover and cook on medium low heat until the bread is lightly browned and cheese is mostly melted, about 5 minutes. Carefully flip the sandwich and cook 2-3 more minutes until the second piece of bread is lightly toasted and the cheese is completely melted.
Serve immediately.
Notes
LeftoversSandwich is best enjoyed immediately after it is made, but leftovers can be stored in the refrigerator for 3 days. Reheat in the microwave, a frying pan or enjoy cold.