Cook the pasta according to package directions, drain and set aside. In a saucepan, combine the milk, flour, onion powder and dill and whisk until well blended. Add the peas and salmon; place over high heat. Bring the mixture to a simmer, stirring constantly.
Reduce heat and continue to simmer and stir gently until the soup thickens slightly, about 2 minutes. Stir in pasta and season with salt and pepper to taste. Heat through and serve.