Peel the eggplant, cut it into 1-inch cubes and arrange them in a single layer on a clean kitchen towel. Sprinkle with salt and set aside for 20 minutes.
Preheat the oven to 350°F and coat large baking sheet with nonstick spray. Blot the eggplant with paper towels and arrange the cubes in a single layer on the prepared baking sheet. Drizzle with a small amount of olive oil (1 to 2 tablespoons), season with freshly ground pepper and roast until tender and lightly browned, 15 to 20 minutes. Set aside.
While the eggplant roasts, bring a large pot of salted water to a boil. Add the conchiglie and cook until tender but not soft (al dente). Drain and set aside.
Heat the milk in the microwave or a separate saucepan until very warm, but not scalded. Set aside.
Heat the butter in a saucepan over medium heat. Add the garlic and cook until fragrant, 1 minute. Add the flour and mix well. Continue cooking for another 2 to 3 minutes, until the mixture is smooth and golden in color. Gradually add the warmed milk, whisking continually until well blended.
Continue cooking, whisking frequently, until the sauce is smooth and thick enough to coat the back of a spoon, 7 to 8 minutes. Scrape down the sides of the pan with a spatula once or twice during cooking to ensure there are no lumps in your sauce. Season to taste with salt and pepper.
Reduce the heat to low, add the fontina and stir until completely melted. Add the goat cheese, sun-dried tomatoes and chives. Stir until creamy and smooth, then add the macaroni and reserved eggplant. Combine well, remove from the heat and allow to stand 5 minutes. Stir again, then serve.