Boil the potatoes in a large pan of boiling water until tender. Drain and mash with the butter.
Mix the flour with the eggs and milk and beat in the mashed potato to make a smooth, thick batter. Season with salt and pepper.
Heat a little of the oil in a frying pan and drop in spoonfuls of the batter, allowing space for them to spread a little.
Cook for 2 minutes then flip the pancakes with a palette knife and cook for another 2 minutes or until golden brown. Continue with the rest of the batter, adding more oil as necessary. Stack the pancakes between sheets of kitchen parchment and cover with a clean tea towel to keep warm.
Mix the horseradish with the cream and season with salt and pepper. 6 Serve the pancakes with the smoked salmon and horseradish cream, topped with caviar and chive stalks.