Preheat the oven to 180ºC / 350ºF / Gas Mark 4. Bring a large saucepan of lightly salted water
to the boil. Add the pasta, return to the boil and cook for 8-10 minutes, or until tender but still
firm to the bite. Drain and return to the saucepan. Add 25g / 1 oz of the butter to the pasta,
cover, shake the saucepan and keep warm.
Melt the remaining butter in a separate saucepan. Add the fennel and fry for 3-4 minutes. Stir
in the mushrooms and fry for a further 2 minutes. Stir in the prawns, then remove the saucepan from
Stir the cayenne pepper into the Bechamel Sauce and add the prawn mixture and pasta.
Grease a large oven proof dish with butter, then pour the mixture into the dish and spread
evenly. Sprinkle over the Parmesan cheese and arrange the tomato slices in a ring around the edge.
Brush the tomatoes with olive oil, then sprinkle over the oregano. Bake in the preheated oven for
25 minutes, or until golden brown. Serve immediately.