Preheat oven to 350F.

Bring 2qts of water to a boil in a large saucepan. Add pasta and simmer, uncovered 6-7 minutes, until the pasta just begins to soften. Drain and set aside.

In a large skillet, cook sausage over medium heat, covered, until firm, 5-7 minutes. Remove from the pan and slice. Set aside.

Add onion and celery to the sausage grease that is left in the skillet. Sauté the vegetables until they begin to soften, 2-3 minutes. Add peppers and continue to saute 2-3 min.

Add flour and stir until moistened.

Add the sliced, cooked sausage and stir to mix.

Add diced tomatoes, milk, tomato paste, and Cajun spice blend. Simmer 4-6 minutes, stirring often, until the sauce has thickened slightly.

Toss the drained pasta with the veggie and sausage mixture, and place everything into a greased, oven-proof, 3 qt baking dish.

Cover with aluminum foil and bake for 10 minutes, until bubbly. Top with mozzarella cheese and return to the oven to bake, uncovered, for an additional 5-7 minutes, until the cheese is melted and golden.