Heat a panini pan and press over medium grill on your stove (or preheat your panini press).
Melt the butter. Lightly brush the sides of the bread with the butter.
Spread the goat cheese onto one slice of bread. Top with chopped basil, then chicken breast, tomatoes and a sprinkle of salt and pepper. Top with second slice of bread.
Press the sandwich on the panini pan/press until lightly browned on both sides.
Cut in half and serve.