Cheesy Chicken Spaghetti Bake This comforting cheesy chicken spaghetti bake combines tender pasta, flavorful vegetables, and succulent chicken topped with melted cheese, making it a perfect family meal. Ingredients Kosher salt (such as Diamond Crystal) Black pepper 8 ounces spaghetti, broken into thirds 4 tablespoons unsalted butter, plus more for greasing 1 small yellow onion, finely chopped 4 ounces white button mushrooms, finely chopped 2 celery stalks, finely chopped 1 medium green bell pepper, finely chopped 2 garlic cloves, minced ¼ cup all-purpose flour 1 cup milk 1 cup low-sodium chicken stock or broth ¼ teaspoon onion powder ¼ teaspoon garlic powder 2 (10-ounce) cans diced tomatoes with green chiles, drained 1 pound cooked chicken, chopped or shredded 2 cups (8 ounces) shredded Cheddar 1 cup (3 ounces) shredded or grated Parmesan Hot sauce, to taste (optional) Directions Step 1 Preheat the oven to 350 degrees with the rack positioned in the center. Grease a 9-by-13-inch casserole dish with butter. Bring a large pot of salted water to a rolling boil. Add the spaghetti and cook until just under al dente, about 9 minutes. Drain and place in a large mixing bowl. Step 2 In a large pan, melt the butter over medium heat. Add the onion, mushrooms, celery, and bell pepper. Sauté, stirring occasionally, until vegetables are tender, about 10 to 12 minutes. Stir in the minced garlic, season with salt and pepper, and cook for an additional 2 minutes. Gradually mix in 2 tablespoons of the flour until smooth; continue adding the remaining flour while stirring until it releases a nutty aroma, about 2 minutes. Step 3 Slowly add the milk in increments of ¼ cup, stirring continuously to avoid lumps. Gradually incorporate the chicken stock while stirring. Add onion powder, garlic powder, 1 teaspoon salt, and ½ teaspoon black pepper. Keep stirring until the mixture thickens, about 5 minutes. Stir in the diced tomatoes, taste for seasoning, and remove from heat. Step 4 Combine the vegetable mixture, chicken, 1 cup of Cheddar, and Parmesan with the spaghetti and mix well. Adjust seasoning to taste and add hot sauce if desired. Transfer the mixture to the prepared casserole dish, spreading it evenly and sprinkling the remaining Cheddar on top. Bake uncovered until the cheese is melted and the casserole is bubbling, about 40 minutes. Allow to cool for 5 minutes before serving.
