Cook the macaroni according to package directions; drain well.
Meanwhile, warm the milk and cream in a small saucepan over medium
heat, or in a glass measuring cup in a microwave oven for about
2 minutes. Do not boil.
In another saucepan, melt the butter and add flour, stirring until
a paste forms. Pour the warmed milk into the butter mixture and
cook, stirring constantly, until thick and creamy. Add cheese a
little at a time, stirring until melted.
Stir in tomatoes, chiles and seasonings. Combine the hot macaroni
and the sauce, blending well. Pour into a buttered, 2-quart casserole
Bake uncovered at 400 degrees F for 35 to 40 minutes, or until
top is nicely browned.