Combine the first 4 ingredients in a small bowl. Butter one side of each bread slice. Divide and top the unbuttered side of 2 of the bread slices with the shrimp mixture. Divide and top the shrimp with the cheese. Top with the other 2 slices of bread, setting them buttered side up.
Set a large, non-stick skillet over medium-low to medium heat. Add the sandwiches and cook 3 to 4 minutes per side, or until the cheese is melted and the bread is nicely toasted. Slice the sandwiches in half or quarters and enjoy.