Begin by boiling salted water in a large pot. Cook the dry spaghetti until it's just under al dente, approximately 8-9 minutes, then drain it.

In a mixing bowl, combine the hot spaghetti with melted butter, grated Romano cheese, and beaten eggs. Press this mixture firmly into a greased pie plate and refrigerate for 30 minutes to set the crust.

In a large skillet over medium heat, cook the bacon until crispy, about 5-7 minutes. Reserve the rendered fat in the skillet, then add diced onion and red bell pepper, sautéing until softened, about 3-4 minutes.

Next, add the boneless chicken and cook until no longer pink inside, which should take around 6-8 minutes, stirring occasionally to ensure even cooking.

In a medium saucepan over low heat, whisk together the whole milk, heavy cream, and egg yolk until well combined.

Gradually stir in the remaining butter and flour, continuing to whisk for 5-7 minutes until the sauce thickens to a creamy consistency.

Season with kosher salt, black pepper, dry mustard, and a few grinds of nutmeg to enhance flavors.

Once your sauce is thickened, fold in the chicken mixture from the skillet into the creamy sauce, ensuring an even distribution.

Stir in shredded Fontina cheese until it's fully melted and incorporated.

Spread a generous layer of ricotta cheese evenly over the chilled spaghetti crust.

Carefully pour the filling over the ricotta layer, spreading it out for even coverage.

Preheat your oven to 350°F (175°C). Bake the pie in the preheated oven for about 40 minutes or until the filling is bubbly and the top is lightly golden.

In the last 10-15 minutes of baking, sprinkle the mozzarella cheese on top and return to the oven until melted and slightly browned.

Once baked, remove the Chicken Carbonara Spaghetti Pie from the oven and allow it to rest for 20 minutes.

Slice and serve this delicious comfort food at your next family gathering!