Boil the sweet potatoes in salted water until soft. Drain and mash.
PREPARE THE SAUCE
In a large fry pan, saute the beef with the onion, garlic, bay leaf and olive oil. Season to taste. Add half the Barilla Bolognese sauce and simmer gently for 5 minutes.
ASSEMBLE THE FILLING
In a large bowl, mix the sweet potato mash, and half the ricotta cheese and egg yolk together with half of the Parmigiano Reggiano and a quarter of the Bolognese sauce. Add salt, pepper and nutmeg to taste.
FILL THE CANNELLONI
Use a piping bag to fill the Cannelloni with the Bolognese mixture.
PREPARE THE DISH
Mix the rest of the ricotta and with the milk to form a cream. In a large ovenproof baking dish, evenly spread a quarter of the Bolognese sauce and half of the ricotta cream across the bottom. Place the cannelloni on top and then cover with the remaining Bolognese sauce. Top with the leftover ricotta cream and Parmigiano Reggiano.
BAKE AND SERVE
Bake in the oven for 20 minutes, and allow to rest for 5 minutes before serving.
