Bring the broth to a simmer in a medium saucepan. Keep warm.

In another large saucepan, heat 1 TBSP of olive oil over medium heat. Add chopped leek, saute for 3-4 minutes.

Add Arborio rice and cook for 2 minutes, constantly stirring.

Stir in the white wine, and cook until the liquid is nearly absorbed, constantly stirring.

Stir in about a cup of broth, then cook until all of the liquid is nearly absorbed, 4-5 minutes. Stir constantly.

Add the remaining broth, around 1/2 cup at a time, stirring the whole time until each portion of broth is absorbed before adding the next. This will take around half an hour.

Stir in half-and-half, salt, and pepper, and cook for 2 minutes.

Remove from heat. In another small, heavy saucepan, bring the balsamic vinegar to a boil over medium heat. Cook until slightly syrupy, about 4 minutes.

Meanwhile, stir the tomatoes, basil, and mozzarella into the rice. Mix to combine well, and pour into a pasta serving dish.

Drizzle the syrupy balsamic over top the risotto, and enjoy!