Fill a large pot with water and bring to a boil over high heat. Add 1/2 teaspoon salt and, while stirring, add the rotini. Return to a boil, reduce the heat to a low boil and cook for 8-11 minutes, or until rotini is al dente. Drain in a colander and set aside.
Meanwhile, heat olive oil in a large non-stick skillet over medium high heat. Add onion and slaw mix. Saute for 10 minutes or until tender. Add smoked sausage, apple and seasoned salt; saute for 5-6 more minutes or until apple is tender. Remove from heat.
Preheat oven to 350 degrees F.
In a separate large pot, melt 4 tablespoons butter over low heat. Add flour and stir to combine. Cook, stirring constantly, for 3 minutes. Increase the heat to medium and whisk in the half and half, a little at a time. Cook until thickened, about 4-5 minutes, stirring frequently. Reduce heat to low; add cheeses, 1/4 teaspoon salt and pepper. Stir until cheese is melted and sauce is smooth. Stir in cooked rotini and cabbage/sausage mixture.
Using 1 tablespoon of butter, grease a 3-quart casserole dish. Pour pasta mixture into buttered dish. Melt remaining 1 tablespoon butter. In small bowl, combine butter with crackers. Sprinkle over the top of the pasta.
Bake at 350 degrees F. for 35-40 minutes, or until top is golden brown. Remove from oven and allow to sit for 5 minutes before serving.
Prep time: 30 minutes
Cook time: 1 hour
Makes 8 servings