Preheat oven to 200ºC (390ºF). Finely shred the potato. Place in a large bowl with the egg, butter, salt and pepper and mix well to combine. Drain off any excess liquid. Press tablespoonfuls of the mixture into the base of 12 lightly greased ½ cup-capacity (125ml) muffin tins and bake for 25 minutes or until golden. Cool on a wire rack.
Place the sour cream and horseradish in a bowl and mix until well combined. Spoon onto the potato pancakes and top with beetroot and chervil to serve. Makes 12.