I got this recipe from the Kraft Foods magazine. It's just another simple to fix casserole. This freezes well.
1 package macaroni and cheese dinner
1 pound ground beef
1 package taco seasoning mix
3/4 cup water
3/4 cup sour cream
1 1/2 cups shredded cheddar cheese, divided
1 cup salsa
Preheat oven to 400 degrees. Prepare dinner according to package directions. While macaroni is cooking, brown meat and drain fat. Add taco seasoning mix and water to the beef and simmer. When macaroni and cheese is prepared, stir in beef, sour cream and half the cheese. Pour into greased 9x13" dish. Top with salsa (I usually just stir this in with the other stuff). Bake uncovered for 20 minutes then add remaining cheese and bake until cheese is melted.