In small pan, saute onions with the butter, just until soft. Set aside.
In seperate saucepan or pot, heat vegetables and chicken broth until boiling.
Lower heat and add milk.
In a small cup, mix a little bit of cold water and the flour until its dissolved (thus eliminating the lumps that may occur if you just dump the flour in the hot vegetables and broth) and mix with the heated broth.
Add onions, curry, parsley, salt, pepper and chicken to the broth and let simmer until it thickens. Add more flour if needed.
Once the sauce thickens to your liking, pour into pie pan and top with pre-made pie crust.
Cut slits in top (and brush with butter if you want).
Bake at 400 degrees until crust is nice and golden.