Preheat your oven to 180 degrees Celsius (350 degrees Fahrenheit).
To prepare the pasta: Prepare the Stellini pasta in accordance with the directions provided on the box by cooking it in a big pot of salted water until it reaches the al dente. Drain, then keep away for later use.
Get the béchamel sauce ready by: To make a roux, melt the butter in a skillet over medium heat and then whisk in the flour until it is completely incorporated. While whisking continuously, gradually add the milk until you have a sauce that is completely smooth. Continue cooking until the sauce reaches the desired consistency. Salt and a dash of nutmeg should be used as seasonings.
The first step in preparing the meat is to heat a little amount of vegetable oil in a frying pan over medium heat. When the onion and garlic have become aromatic and tender, add them to the pan and sauté them. Turn the heat up to high, add the meat that has been minced, and continue to cook it until it is browned. In the event that it is required, season with meat seasoning and more salt. After a few minutes of simmering, stir in the tomato sauce; continue to cook.
Put together the dish by: Half of the cooked pasta should be layered in a baking dish, followed by half of the meat combination, and then half of the béchamel sauce should be layered on top of that. The layers should be repeated one more.