Preheat oven to 350°F / 180°C / Gas Mark 4 Preheat oven to 350°F.
Slice each croissant open, starting from the front and leaving the back unbroken, and butter each half. Divide the salami and arrange over the bottom of each croissant. Cover with the Gruyere cheese and season to taste with salt and pepper.
Place in the preheated 350°F oven for 10 minutes or until the croissants are hot through and the cheese has melted. Cut in half and serve hot.
Delicious when served with a green salad and a glass of Italian wine.