Make a soffritto by gently sweating the onion in a fairly generous amount of olive oil, in a shallow terracotta tiella (see photo) or a braiser. When the onion is soft and translucent, add the garlic, mix and let it simmer for just a few moments. (Add the red pepper flakes now, if using.)

Now take a food mill and place it over the pot, then pass the canned tomatoes through the mill into the pot. (If using the passata, just add it to the soffritto.) Add the basil leaf and let the tomatoes simmer, still over gentle heat, for about 10-15 minutes, until they have cooked down a bit and formed a sauce.

Now crack open your eggs, one by one, and gingerly drop them into the tomato sauce. (I usually open the eggs into a small bowl or cup and then slide the egg into the sauce. This helps avoid breaking the yolk and, if it does break, you can discard it before it's in the sauce.) Cover the pan and continue simmering the eggs in the sauce until the whites are set and the yolk has 'glazed over' but are still soft inside.

Serve immediately with some nice crusty bread to soak up the sauce.