Boil water in sauce pan, then add in macaroni. Stirring ocassionaly. Boiling 8-10 minutes.
Add frozen vegetables 2 minutes before the end of boil time.
Drain and return to sauce pan.
Add in butter, milk and cheese. Stir until mixed.
Pour into casserole dish.
Add tuna and stir into macaroni mixture.
Sprinkle crushed buttery crackers over macaroni mixture.
Serve immediately.