Make a béchamel sauce by melting the butter in a saucepan on a medium to high heat and whisk in the flour. Gradually add the milk whisking the liquid into the paste until its absorbed, then repeat until you have a smooth looking sauce
Add the grated cheese and whisk into the sauce then add the mustard. Season to taste.
Cut the Salmon into bite size pieces and add them into the bechemel sauce
Cook on a medium heat, stirring occasionally for 4-5 minutes
Follow the instructions for your Fettuccine from the pack, usually just a few minutes in boiling water with a little salt and a dash of olive oil. When the pasta is cooked, drain it and place it back in the pan. Add a little of the sauce to the pasta, stir gently
Plate the pasta, then pour the Salmon & cheese sauce on top, garnish with a little fresh parsley & enjoy