1. Heat a large pan of salted water and cook your pasta according to packet instructions (generally between 10 and 12 minutes).
2. In a large saucepan, gently melt the butter and then add the flour. Whisk together over a low heat for a minute but be careful not to let it burn.
3. Pour in the milk gradually, whisking continuously until you have a thick white béchamel-style sauce.
4. Remove from the heat and whisk in half the grated cheddar then add the mustard, tuna, sweetcorn, spring onion, tabasco and salt and pepper to taste.
5. Stir through the pasta until all the pieces are covered then put in a baking dish. Top with the cheese and cook at 180C/Gas 4 until melted, golden and bubbling.