Ingredients

Step by step

1. Melt the butter in a medium pan, add the flour and stir well. Cook, stirring over a low heat, for a couple of minutes. Gradually add the milk, stirring well between each addition until smooth, followed by the mustard. Still stirring, increase the heat to medium and bring to the boil. Cook for 5 minutes until thickened and smooth. Remove from the heat, stir in two- thirds of the combined cheeses and season to taste. Stir in 2 teaspoons of truffle oil then cover with a lid and set aside.
2. Heat half the olive oil in a large non-stick frying pan. Add half the mushrooms and half the thyme leaves, season, and cook over a high heat for 3-4 minutes, stirring now and then until golden. Tip onto a plate and repeat with the remaining oil and mushrooms. Turn off the heat, add all the mushrooms back into the pan, along with the garlic and 2 teaspoons of truffle oil and stir together. Set aside.
3. Meanwhile, cook the pasta in a pan of boiling water for 7 minutes or until al dente, then drain. Preheat the oven to 200°C, fan 180°C, gas 6.
4. Add the cooked pasta and most of the mushrooms to the cheese sauce and mix well. Tip into a large baking dish (about 30cm x 20cm) and top with the rest of the mushrooms. Mix together the breadcrumbs, remaining cheeses and thyme leaves and sprinkle over the top. Season with black pepper and drizzle with a final 2 teaspoons of truffle oil or extra-virgin olive oil if you prefer.
5. Bake in the oven for 25-30 minutes or until golden and bubbling.