Cook pasta according to package directions; drain.
Brown ground beef in a large skillet over medium-high heat.
When the ground beef is completely cooked, drain off the fat, and return to skillet.
Add taco seasoning and amount of water indicated on the taco seasoning package.
Once liquid has simmered down a bit, add cream cheese, milk, and Velveeta and stir to combine. Cook until cream cheese is melted and mixture is thick and bubbling.
Pour meat and cheese mixture into a large bowl and add pasta.
Garnish with sour cream, tomatoes, cheese, and lettuce as desired.