Combine all spices for Cajun Spice Mix. Mix well. Store in a tightly covered container.
Preheat oven to 350°F.
Cook pasta according to package directions to al dente. Drain well and set aside. Melt 2 tablespoons butter in pasta stock pot. Add onion, bell pepper and celery; cook for 5 to 7 minutes, until tender. Add remaining butter, stirring until melted. Add flour, stirring until well blended; simmer mixture for one minute. Gradually add milk, stirring constantly until thickened, about 3 to 5 minutes. Stir in 1 tablespoon Cajun Spice Mix.
Gradually add both cheeses to sauce, stirring until melted. Stir in drained pasta and andouille sausage. Pour into greased 2 to 3-quart baking dish. Combine corn bread crumbs and 1/2 teaspoon Cajun Spice Mix. Mix well and spread over macaroni and cheese.
Bake for 25 minutes until bread crumbs are lightly browned.
Twelve ounces of cooked crayfish meat can be substituted for the andouille sausage. Panko bread crumbs may be used in place of the corn bread crumbs.