Baked Macaroni and Gouda Cheese with Italian Sausage

Preheat the oven to 350°. In a large pot of boiling salted water, cook the pasta until al dente, about 11 minutes.

Meanwhile, heat a large, heavy-bottomed saucepan over medium-high heat. Add the sausage and cook, stirring and breaking up the meat with a wooden spoon, until no longer pink, 3 to 4 minutes. Transfer the sausage to a large bowl and wipe the saucepan clean.

Add the pasta and 1 cup caramelized onions to the sausage and stir to combine. In a medium saucepan or a microwave oven, heat the milk until steaming.

Return the large saucepan to the stove, add the butter and melt over medium heat. Add the flour and cook, whisking constantly, for 3 minutes. Whisk in the hot milk, 1/4 cup at a time, and continue whisking until the sauce is smooth and thick and comes to a simmer. Add 2 1/2 cups cheese, remove from the heat and whisk until the cheese is melted, about 2 minutes; season to taste with salt and pepper. Add the cheese sauce to the pasta mixture and stir to combine.

Butter a 9-by-13-inch baking dish and add the pasta mixture in an even layer. Sprinkle the remaining 1/2 cup caramelized onions and 1 1/2 cups cheese on top. Bake until golden and bubbling, about 40 minutes. Remove from the oven and let rest for 10 minutes before serving.