Start by preheating your oven to 350°F and greasing a 9x13 inch baking dish. While the oven heats, cook the bacon in a large skillet over medium-high heat until it's crispy, about 8-10 minutes. Transfer the cooked bacon to a paper towel-lined plate to cool, then crumble it into small bite-sized pieces. Set aside. This step ensures the bacon is ready to incorporate into the creamy sauce and gives you time for the oven to reach temperature.

Bring a large pot of salted water to a boil and cook the spaghetti according to package directions until al dente, then drain and set aside in a large bowl. While the pasta cooks, in a separate small bowl, whisk together the melted butter (cooled slightly), eggs, and parmesan until well combined. Once the pasta is drained and still warm, pour the egg mixture over it and toss thoroughly to coat every strand—the residual heat will gently cook the eggs and create a silky coating that helps bind everything together.

In a large mixing bowl, combine the room-temperature cream cheese, cream of chicken soup, and sour cream, stirring until smooth and well blended. I find that using room-temperature cream cheese makes this step much easier and prevents lumps—cold cream cheese can be stubborn! Add the shredded chicken, crumbled bacon from Step 1, and 2 cups mozzarella to the cream mixture. Finally, sprinkle in the Italian seasoning, garlic powder, onion powder, salt, pepper, and red pepper flakes, stirring until everything is evenly distributed and the sauce is creamy and cohesive.

Spread half of the coated spaghetti from Step 2 in an even layer on the bottom of your prepared baking dish. Pour half of the creamy sauce mixture from Step 3 over the pasta and spread it evenly. Top with the remaining coated spaghetti from Step 2, then finish with the remaining sauce from Step 3, spreading it to cover all the pasta. I like to stir the sauce together gently as I layer—it helps ensure even flavor distribution throughout the casserole.

Sprinkle the remaining 1/2 cup mozzarella evenly over the top of the assembled casserole. Transfer to the preheated 350°F oven and bake for 30-45 minutes, until the top is golden brown and the edges are bubbling—you'll know it's done when a knife inserted into the center comes out hot and the cheese is melted and slightly browned. Let the casserole rest for 5 minutes before serving; this allows the layers to set slightly, making it easier to portion without falling apart.