First thing, you need to make the Alfredo sauce, this is easy. Melt the Cream cheese and butter in a saucepan, stir in the milk, season with salt and pepper. See, that was easy.
Add the sauce you just made to the slow cooker, then add the mushrooms, chicken stock, nutmeg, and season with salt and pepper as desired, mix.
Add the chicken to the slow cooker and stir to coat. Cook on Low setting for 5-6 hours.
Just before the chicken is done, cook your pasta and drain, splash a bit of olive oil on the pasta to prevent sticking and set aside.
When the chicken is done, stir the Parmesan cheese into the slow cooker, serve over hot pasta, sprinkle each serving with sliced spring onion.