Take 4 slices of bread (preferably Italian or any crusty bread) and spread a thin layer of butter on one side of each slice.
On the unbuttered side of two slices, place 50 grams of sliced mozzarella cheese, 50 grams of sliced tomatoes, a few basil leaves, and a pinch of salt and pepper.
Place the remaining two slices of bread on top, buttered side facing out.
Preheat a panini press or a non-stick pan on medium heat.
Place the sandwiches on the panini press or pan and cook for 3-4 minutes on each side until the bread is golden brown and crispy, and the cheese has melted.
Remove the panini from the press or pan, let it cool for a minute, and then cut into halves or quarters.