Ingredients :

• Penne rigate — The ‘rigate’—with the ridges—is not just a detail. These grooves hold the creamy sauce much better than smooth penne. If you only have smooth ones, it works, but rigate truly change the final texture.
• Canned tuna in water — In water, not in oil. Tuna in oil will make the sauce greasy and unbalanced. Drain it thoroughly in a sieve by pressing with the back of a spoon—excess water is the enemy of a sauce that sets well.
• Full-fat crème fraîche — Thick, at least 30% fat. Liquid cream will make the pasta soggy and the sauce won’t set. Avoid low-fat cream too—it curdles during cooking and gives a grainy result.
• Dijon mustard — One tablespoon. You won’t taste it directly in the finished dish, but without it, the sauce is bland. It’s what provides that slightly sharp background that makes people go back for seconds.