Next, pour 4 tablespoons of olive oil into a frying pan and sauté the onions and garlic for 2 minutes.
Add the ground beef and fry for about 5 minutes.
Next, pour in the passata, a pinch of salt, a couple twists of black pepper and the basil. Let it all simmer together between 15 and 20 minutes.
While the meat is simmering, you can prepare the topping and preheat the oven to 200ºC.
Melt butter in a saucepan. When completely melted, whisk in the flour for a minute or two. When completely dissolved, you can add the milk. This step should be done slowly and carefully so as to avoid lumps.
Add salt, pepper and nutmeg and simmer for five minutes, until the sauce has thickened.
Remove from the heat and add the Parmesan cheese and cherry tomatoes, stirring them all together.
Take the meat and tomato mixture, stuffing it inside the canneloni.
Gently place the canneloni side-by-side in a large baking dish, pouring the cheese sauce on top.
Bake for 20 minutes and serve piping hot. But be careful not to burn your mouth!
Recipe by Mamma Mia! at http://recipes.hellomagazine.com/italianfood/20120912/beef-canneloni/