Pour water into a larger pot, add salt and bring to a rapid boil.
While water is heating cut the chicken breasts into small 1" cubes and season with salt and pepper.
Coat the bottom of a small frying pan with the oil and add chicken cubes making sure the chicken is evenly coated with the oil. Cook until golden brown and done on inside. (About 7 minutes on medium high heat.) You can also boil your chicken breasts whole if you prefer.
If using left over chicken there is no need to reheat it. Simply cut it into cubes or shred it with a fork.
Set chicken aside.
Place spaghetti in the rapidly boiling water and cook until pasta is tender. (About 10 minutes.)
Cut Velveeta into small cubes. This will allow it to melt faster
Strain pasta and place back into the pot.
Add cooked chicken, Velveeta, Rotel (undrained), cream of chicken soup and milk.
Place pot on medium heat and stir until the Velveeta is completely melted! (If mixture is too thick for you liking you can add more milk to thin it out.)