Sausage & Caramelized Fennel Mac and Cheese

Preheat the oven to 425°. Bring a large pot of salted water to a boil. Add the pasta and cook until al dente, about 11 minutes. Remove from heat. Reserve 1 cup of the pasta cooking water, drain, then return the pasta to the pot.

Meanwhile, heat a large skillet over medium-high; add the sausage and break into small pieces with a wooden spoon. Cook, stirring often, until sausage is cooked through and browned, 6 to 7 minutes. Using a slotted spoon, remove the sausage to a paper towel–lined plate and return the skillet to the stove.

Reduce heat to medium and add 4 tbsp. butter to the skillet. Once melted, stir in sliced fennel, 1 tbsp. thyme, 1 tsp. kosher salt, and 1/2 tsp. pepper. Cook, stirring frequently, until the fennel is very soft and golden brown, about 15 minutes. Remove skillet from heat; stir in the brandy and 1/4 cup of water. Return skillet to the heat and cook, scraping the bottom of the pan to release any brown bits, until the liquid evaporates, 3 to 4 minutes.

Sprinkle the flour over the fennel and stir until combined. Slowly pour in the milk and cook, stirring frequently, until thickened and the flour taste is almost gone, about 5 minutes. Stir in the Gruyère, mozzarella, and 1/2 cup of the Parmesan until melted (the sauce will be thick but will loosen up when the pasta water is added).

Pour the cheese sauce into the pot with the pasta. Add the reserved pasta water, sausage, and remaining 1 tsp. salt, stirring until well coated. Transfer pasta to a 9-by-13-inch (3-quart) baking dish.

Melt the remaining 3 tbsp. butter in a medium microwave-safe bowl for about 30 seconds. Stir in the panko, fennel fronds, and the remaining 1 tbsp. thyme and Parm. Season with remaining 1/2 tsp. pepper and more salt, if desired. Sprinkle over the pasta and bake until bubbling and golden brown, about 20 minutes. Let rest for 10 minutes before serving.