Put the guanciale in a cold frying pan, then turn the heat to medium. Cook for 4-5 mins, stirring occasionally until the fat has rendered and the guanciale is crisp and golden. Remove from the pan using a slotted spoon and set aside on kitchen paper to drain. Keep the fat in the pan and remove the pan from the heat.

Whisk the eggs, parmesan and plenty of black pepper together in a medium heatproof bowl. Carefully pour in half of the hot guanciale fat from the pan, whisking continuously – it is important to do this slowly and keep it moving so the eggs don’t scramble.

Put the pan back over a low heat, then pour the beans into the remaining guanciale fat. Turn up the heat to medium and cook for 3-4 mins until steaming, then remove from the heat and pour in the egg and parmesan mixture gradually, mixing continuously. Mix in the few tablespoons of the bean liquid from the jar to loosen the sauce to a silky consistency. Return most of the guanciale to the pan, saving a few pieces for garnish. Serve topped with more parmesan, the reserved guanciale and a grinding of black pepper.