Method
Cut the haddock into small chunks and place in a food processor with the parsley, cream cheese, mustard and lemon juice. Pulse briefly until broken down. Add the mashed potato and pulse again until just combined. Season well and chill.
Bring a pan of water to the boil. Cook the eggs for 6 1/2 minutes, then cool under cold running water and peel.
Divide the haddock mixture into eight portions. Flatten one portion in your hand, place an egg in the centre, and cover with another portion. Shape carefully to seal the egg completely. Repeat with the remaining eggs.
Place the flour, beaten eggs and breadcrumbs into separate bowls. Coat each Scotch egg in flour, then egg, then breadcrumbs. Chill until ready to cook.
Heat the oil to 175°C. Fry the Scotch eggs in batches for 6–8 minutes, turning until golden and crisp. Drain on kitchen paper.
To make the mayonnaise, place the egg yolks, garlic, lemon zest and juice, and mustard in a food processor. Blend briefly, then slowly drizzle in the combined oils until thick and emulsified. Stir in the chives and season. Serve with the Scotch eggs.