Make the breadcrumbs in a food processor then add the 2 oz cold butter and whizz briefly. Stir in the ground almonds, mixed herbs and garlic and whizz again.
Add the flaked almonds or pine kernels and mix all together well. Push down very firmly in a flat swiss roll tin.
Bake in a fan oven preheated to 180 C Gas 7 for 12-15 mins until crisp and golden brown.
Meanwhile make the topping. Heat the butter in a saucepan and saute the mushrooms until tender. Add the bechamel sauce and simmer over a low heat for 10 minutes. Season well with salt, pepper and nutmeg.
Spread the mixture over the croustade. Top with sliced tomatoes and sprinkle with a little more salt and pepper.
Return to the oven for 10-15 minutes to heat through. Sprinkle with the parsley before serving with a green salad.