Step 1Bring 5 quarts salted water (add 1 tablespoon salt and stir so the salt dissolves in the water) to boil. Add macaroni and again give a stir so macaroni doesn't stick to bottom of pot. Set a timer for 8 minutes and test macaroni for doneness by spearing a piece with a fork, running it under cold water and taking a bite. If it is tender it is done; if it still seems firm, give it another 2 minutes of cooking and test again. Drain macaroni. Place in bowl and, if you are making it ahead of time and don't plan to serve it right away, take a fork and stir it, then let it sit while you make the sauce.
Step 2Melt butter in small saucepan over medium heat. Stir in flour and stir constantly until butter and flour are smooth and blended. Add curry powder and continue cooking and stirring a couple of minutes; then slowly add milk, stirring constantly so no lumps form. If you have trouble blending smoothly, brisk stirring with a whisk will help. Stir sauce so it thickens, about 5 minutes, taking care it does not burn. Remove from heat and add salt, a little at a time, stirring and tasting, until you like the taste. Add pepper to taste too.
Step 3Pour sauce over macaroni and toss until blended. Add cilantro and serve.