Tuna Pasta Bake with Sweetcorn and Cheddar

Step 1. Preheat the oven to 200°C. Put a large pan of well-salted water on to boil and lightly butter a medium baking dish, about 20 x 30cm.

Step 2. Cook the penne in the boiling water for 2 minutes less than the packet says, so it is just underdone. Reserve about 100ml of the pasta cooking water, then drain the pasta well and set aside. Do not rinse it.

Step 3. While the pasta cooks, melt the butter in a large sauté pan or saucepan over a medium heat. Add the onion with a small pinch of salt and cook for 6-8 minutes, stirring now and then, until softened but not browned. Stir in the garlic and cook for 30 seconds.

Step 4. Sprinkle in the flour and stir for 1 minute to cook it out. Gradually add the milk, whisking well after each addition so the sauce stays smooth. Bring to a gentle simmer and cook for 3-5 minutes, stirring, until thick enough to coat the back of a spoon.

Step 5. Take the pan off the heat. Stir in the Dijon mustard, 100g of the cheddar, the lemon juice and a good grind of black pepper until the cheese has melted. Taste and add a little more salt if needed.

Step 6. Fold the drained tuna, sweetcorn, peas and cooked pasta into the sauce. Mix gently so the tuna stays in soft flakes. If the mixture looks very thick, loosen it with a splash or two of the reserved pasta water. Spoon everything into the baking dish and spread it out evenly.

Step 7. Scatter over the remaining 50g cheddar. Bake for 18-22 minutes, until bubbling around the edges and golden on top.

Step 8. Rest the pasta bake for 5 minutes before serving so the sauce settles slightly. Serve hot with extra black pepper if you like.