Cook the macaroni according to the package instructions until al dente. Drain and set aside.
Preheat the oven to 375 degrees F.
In a heavy-bottomed saucepan over medium heat, melt the butter. Add the flour, whisk until a paste is formed and cook for 1 minute. Slowly add 1/4 cup of the milk at a time, whisking constantly, until you've added 2 cups. Whisk in the soup base or bouillon, garlic powder and pepper.
Slowly add the Colby-Jack blend, cream cheese and 1 cup of the Cheddar cheese, making sure the cheese melts between each addition. When the cheese is completely melted, check for consistency; add up to an additional 1/2 cup milk if needed. Stir to completely combine.
In a large mixing bowl, combine the drained macaroni and 2 cups of the cheese sauce. Transfer the macaroni mixture to the chilled springform pan of Andouille Dressing, spreading and packing the contents evenly. Spread 1/2 cup of the cheese sauce over the top with the remaining 1 cup shredded Cheddar.
Bake until heated through, about 35 minutes. Turn the oven to broil and broil until the top is crisped, another 5 to 7 minutes. Let stand for 15 minutes before removing from the pan and serving.
Preheat the oven to 400 degrees F. Spray a 10-inch cast-iron skillet with cooking spray.
To make the cornbread, add the milk, butter and 1 of the eggs to a large mixing bowl and whisk together. Add the cornmeal, flour, sugar, baking powder and a pinch of salt and stir to combine; the batter should look lumpy. Transfer the batter to the greased skillet and bake until golden brown on top, 22 to 25 minutes. Let cool. Keep the oven at 400 degrees F.
Meanwhile, lightly grease two 9-inch springform pans with cooking spray.
Put a pan over medium-high heat and add just enough oil to coat the bottom. Add the sausage and cook until crisp around the edges, 5 to 7 minutes. Using a slotted spoon, transfer the sausage to a paper towel-lined plate to drain. To the same pan, add the onion, green pepper, celery and garlic and cook until the veggies are tender, 5 to 7 minutes.
Crumble the cooled cornbread into a large mixing bowl. Add the cooked veggies and sausage and mix together gently. Beat the remaining egg in a small bowl. Add it to the cornbread mixture with the sage, soup base or bouillon, pepper and 1/4 teaspoon salt; mix together gently. Add the broth 1/4 cup at a time until the dressing reaches the desired consistency. It should be loose but not runny--3/4 to 1 cup will be plenty.
Transfer the dressing to the prepared springform pans. Bake until cooked through, 25 to 30 minutes. Let cool completely.