Apple Sausage Mac And Cheese

Preheat oven to 350 degrees F. Coat a oval or 9×13 baking dish with cooking spray. Bring a large pot of salted water to a boil. Add the pasta and cook until al dente. Drain and set aside.
Meanwhile, melt the butter in a large saucepan over medium heat. Add the onion and cook until soft, about 3 minutes. Add the sausage, mustard powder, cayenne pepper and salt and cook until the sausage is golden, about 3 minutes. Whisk in the flour and cook, stirring, until lightly toasted, about 2 minutes. Stir in the apple juice and cook, stirring occasionally, until thickened slightly, about 8 minutes.
Slowly stir about three-quarters each of the Monterrey jack and cheddar cheese into the sauce until smooth. Remove from the heat. Stir in the pasta and sour cream. Pour the mixture into the prepared baking dish. Sprinkle with the crushed crackers and remaining cheese. Bake until golden brown around the edges, 25 to 30 minutes.