STEP 2 Boil 600g rigatoni for 2 mins less time than stated on the pack.
STEP 3 To make the sauce, melt 50g butter in a saucepan and stir in 50g plain flour.
STEP 4 Cook for 1 min, then gradually stir in 600ml milk to make a thick white sauce.
STEP 5 Remove from the heat and stir in all but a handful of the 250g grated cheddar.
STEP 6 Drain the pasta, mix with the white sauce, two 160g drained cans tuna, one 330g drained can sweetcorn and a large handful of chopped parsley, then season.
STEP 7 Transfer to a baking dish and top with the rest of the grated cheddar.
STEP 8 Bake for 15-20 mins until the cheese on top is golden and starting to brown.