Poach the salmon in the milk for 5 minutes until lightly cooked then drain the milk into a saucepan and flake the salmon before mixing with the creme fraiche and dill. Season to taste.
Cool the broccoli until just cooked and cook the pasta for ⅔ of the cooking time, according to the instructions. Drain and cool.
Make the cheese sauce by adding the flour and butter to the reserved milk then whisking over a medium heat until thickened. Add the grated cheese, check the seasoning and add the nutmeg before pouring onto the base of an oven proof dish.
Spoon the salmon mixture into the shells and arrange in the dish before adding the broccoli.
Add the grated Parmesan and more cheese if liked then bake at 180 for 20 minutes.