Step 1

1 Heat the oven to 200°C/fan 180°C/gas 6 and line a 12-hole muffin tin with muffin cases (silicon cases work best).

Step 2

2 Rinse the grated potatoes under running water. Drain, then squeeze out as much water as you can, using a clean cloth (you may need to do this in batches).

Step 3

3 Heat a large non-stick frying pan. When hot, add the pancetta or bacon and fry until crisp. Remove with a slotted spoon and transfer to a mixing bowl. Drain off the fat from the pan, then add the potatoes and onion to the pan and fry for 5–8 min, using a fork to break up any bits that stick together (add a spoonful of water if necessary), until browned and tender. Transfer the mixture to the bowl with the pancetta or bacon and combine.

Step 4

4 In a large bowl, whisk the egg yolks with the flour using a balloon whisk, then season. Slowly pour in the milk, whisking to combine. Stir the potato mixture and chives through the batter.

Step 5

5 In a separate, spotlessly clean bowl, use an electric hand mixer to whip the egg whites to stiff peaks, then gently fold through the potato batter until just combined. Spoon into the muffin cases and bake for 10–12 min until puffed, golden and springy to touch.

Step 6

6 Remove the tin from the oven, leave the muffins to cool for a few min (like soufflés, they’ll sink a little), then serve while still warm with 1 teaspoon ketchup per muffin.