Preheat the oven to 180°C. Line a 20 cm round cake tin with aluminium foil and grease it with butter.
Cook the potatoes until just done, drain and rinse under cold water. Drain and leave to cool. Peel the potatoes and grate roughly into a mixing bowl.
Stir in the eggs, herbs, spring onions, red pepper and half the cheese. Season with salt and pepper to taste. Lightly press half the potato mixture onto the bottom of the prepared tin.
Blend the filling ingredients in a food processor until mixed but still slightly coarse. Spread the filling on top of the potato layer and cover with the remaining potato mixture. Sprinkle the remaining cheese on top and bake for 60 minutes or until firm
Leave the cake to cool in the tin for 10 minutes before turning out. Cut into slices and serve with mustard or tomato and chilli sauce and a fresh green salad.