In a large pot, boil the pasta for about 7 minutes, until al dente. While pasta is cooking, assemble the sauce in a deep saucepan.
Place butter in the saucepan and let melt. Add flour and mustard to butter and cook, whisking constantly for about 5 minutes over medium-low heat. Add milk and dried spices. Simmer for about 10 minutes, whisking constantly until mixture thickens. Add 3/4 of the cheese and let it melt.
Add the pasta to the pan and mix thoroughly. Place mixture into a greased oven-safe 2- to 3-qt. casserole dish. Top with remaining cheese.
Crumble the cornbread muffins into small pieces resembling bread crumbs and mix with about 2 Tbsp. melted butter. Place buttered muffin crumbs on top of cheese.
Bake in a preheated 350-degree oven for 30-40 minutes or until bubbly and golden.
NOTE: This can be made the day before. Prepare dish up to and including placing pasta mix into the casserole dish. Refrigerate. When ready to bake, add toppings. Bake an extra 10 minutes when dish has been refrigerated.