Start by turning on the oven to 135°C, air ventilation and rack set in the middle.
Put a large roasting pan on medium heat over 2 gas burners and add the butter. After a minute add the garlic and the onions sauté for 5-6’ until soft and fragrant. Halfway add the chili flakes and stir.
Add the tomato paste along with the chili flakes and stir well for the paste to cook for about 3 more minutes. Add the tomato passata along with the chicken broth, stir and bring to a boil. Cover tightly with foil and place in the oven cooking for 4 hours, stirring the sauce every 45 minutes. Go up to 5 hours for a thick consistency of the sauce.
Remove from the oven, uncover, season with the salt and pepper and add the oregano. Add the sugar along with the Parmigiano Reggiano, give it a good stir and toss in the pasta of your choice, preferably Bucatini type.
If not using immediately, you can place the sauce in sterilized airtight glass jars and refrigerate for couple of weeks or freeze for at least 3 months.