Cook the pasta in boiling, salted water, about 75% of the recommended cooking time - you want it to be very al dente, or it will overcook later on.

Drain pasta well and dump into a buttered 3 quart casserole dish.

Remove Chorizo from casings and saute until done, but not crisp, stirring to break it up as it cooks. Drain and reserve any drippings in the pan and add the chorizo to the pasta in the casserole dish.

Place 2 tablespoons of the reserved drippings from from the sausage back in the saute pan, and add the celery, red pepper, chilies and the garlic. Season with a sprinkle of kosher salt. Saute about 5 minutes, stirring often enough so it cooks evenly.

Remove from heat, and stir in the sliced scallions. Add to meat and pasta and stir to combine everything.

In the same saute pan, melt the butter, and whisk in the flour, keeping over low heat - stir and cook for about 1 minute.

Slowly add in the milk, then the 1/2 teaspoon salt, plus a few grinds of pepper, raise heat a bit, and stir and cook until hot and thickened.

Stir in the cheese and remove from heat when about half of cheese is melted. Continue to stir off the heat until cheese is fully melted.

Stir in the cumin and paprika - taste and add salt if needed.

Fold cheese sauce into the ingredients in the casserole dish.

Use a damp paper towel to clean edges of dish so that the drips don't burn in the oven.

Bake in the oven, at 350º, for about 40 minutes, until very bubbly with a nice crusty edge all around. Cool for a bout 5 minutes before serving.