This takes ten minutes max. We've had a busy day today and this is what I chucked together. With thanks to Nigel Slater, who provided the idea.

Put a pan of your favourite short pasta on to boil in salted water. 250g for two people.

Drain a jar of tuna in olive oil, preferably yellowfin (albacore). If you have tuna in spring water, throw it away unopened.

Put tuna in a bowl and add the following: a tablespoon of nonpareil capers (never use any capers bigger than those). Two cloves of garlic, finely sliced (throw your garlic crusher away - worst bloody invention ever). A helping of chopped fresh parsley (don't arse about: tear the leaves off the parsley, put them into a mug and snip away like mad for one minute with a pair of scissors). Freshly-ground black pepper. A little bit of salt, only if your tuna is unsalted. Five tablespoons of full-fat creme fraiche. Nigel uses double cream, but trust me on this. Mix up everything roughly. You want a few visible tuna flakes.

Drain the pasta and retain a mug of pasta water (you'll need some to loosen the sauce).
Mix the pasta and the tuna mix together. Use pasta water to loosen. I've never managed without it. Serve in warm bowls. Heresy coming up: serve with Parmesan. True Italians would kill me for that, but it works.