Melt the butter in a non-stick saucepan over medium heat.

Once the butter has melted, promptly incorporate the flour all at once, stirring continuously with a wooden spoon for approximately one minute until a creamy consistency is achieved.

Gradually pour in the hot milk, taking care to maintain a steady stream while whisking vigorously to prevent lumps from forming.

Season the mixture with salt, pepper, and a hint of nutmeg, then continue stirring for a few minutes until the cream begins to thicken.

Next, add 60 grams of finely grated Parmesan cheese and the fragrant sage leaves, folding them gently into the cream.

Once fully incorporated, remove the saucepan from the heat and set it aside.

In a separate pot, cook the rigatoni pasta according to the package instructions until it reaches an al dente texture, ensuring a slight firmness to the bite.

Drain the pasta thoroughly, discarding the cooking water.

Transfer the cooked rigatoni to a large bowl and toss it with a drizzle of olive oil to prevent sticking.

Spread the pasta evenly onto a baking sheet, ensuring it is in a single layer.

Preheat your oven to 180 °C (356 °F).

Prepare a 22-centimeter springform pan (9-inch) by lining the bottom and sides with baking paper, then lightly brush the interior with a thin coat of olive oil. Position a round pastry cutter in the center of the mold, creating a designated space for the hole in the final pie.

Carefully arrange the rigatoni vertically around the mold, standing them upright and filling the pan. Ensure the rigatoni are tightly packed together, creating a visually appealing pattern.

Carefully pour the prepared Parmesan cream over the arranged rigatoni, taking care to ensure the cream fills the hollow spaces within each pasta tube.

Once the oven has reached the desired temperature, place the assembled pie on the middle rack and bake for approximately 10 minutes.

After the initial baking period, remove the pie from the oven and evenly cover the top with shredded mozzarella cheese. Sprinkle the remaining Parmesan cheese over the mozzarella, creating a delightful cheesy crust. Return the pie to the oven and continue baking for an additional 5 minutes, or until the cheese has melted and developed a golden-brown color.

Once the baking process is complete, carefully remove the pie from the oven and allow it to cool slightly on a wire rack. Gently release the springform pan ring, revealing the beautifully crafted rigatoni pie.

To serve, slice the pie into wedges, much like cutting a cake, and present it as an impressive and flavorful main course.

Enjoy the delightful combination of perfectly cooked rigatoni, creamy Parmesan sauce, and melted cheese in every bite.