|2.5 ml||mustard — powder|
|sea salt and freshly ground black pepper|
|150 g||cheddar cheese — grated|
|65 g||pecorino cheese — grated|
Preheat the oven to 160°C.
1. Bring a saucepan of lightly salted water to the boil. Add the pasta and cook for 10 minutes. Drain and rinse the pasta under cold water for 30 seconds.
2. Cheese sauce: Heat the oil in a saucepan and add the flour, mustard powder, salt and pepper. Stir well. Slowly whisk in the milk. The sauce will start to thicken as it comes to the boil. Simmer for 2 minutes, then remove from the heat.
3. Add the grated cheese and stir until melted. In a large bowl, combine the pasta with the sauce and mix well. Transfer to a casserole dish and use a wooden spoon to smooth the surface. Arrange the sliced tomatoes on top.
4. Place in the oven for 20 minutes or until the edges and the top begin to harden slightly.