Pour stock into a medium saucepan and bring to a boil.
Heat the olive oil in a large, deep pot.
Add the chopped onion and saute over low heat for 5 minutes, until softened.
Add the minced garlic and saute for one more minute; do not burn.
Stir in the arborio rice and cook, all the while stirring continuously, for 2 minutes until all of the rice are coated with oil.
Stir in the chopped tomatoes.
Add a ladleful of the hot stock and cook, stirring continuously until absorbed.
Continue to add the hot stock, a ladleful at a time, stirring continuously until each addition of stock is absorbed, for about 20 minutes.
When the rice is nearly cooked, add the torn basil leaves.
Season generously with sea salt and freshly ground black pepper.
Remove from the heat.
Stir in the butter.
Stir in the buffalo mozzarella.
Stir in the Parmigiana
Transfer to a warm serving dish.
Garnish with basil leaves.
Serve immediately.