1) Begin by heating the chicken broth over medium heat until simmering. Then reduce heat to low.
2) Melt two tablespoons of butter in a large saucepan over medium heat, add onions, and cook until tender.
3) Add rice to saucepan, stirring to coat for approximately two minutes. Continue cooking rice until it is a pale, golden color.
4) Add wine, stirring constantly until the wine is fully absorbed.
5) Add a ladle of broth and stir frequently until it is absorbed.
6) Continue adding one ladle of broth at a time and stirring frequently until you have used almost all of the broth. Add a small amount of butter with each ladle of broth. Cook until rice is al dente. (This should take approximately 20-25 minutes)
7) When adding the last ladle of stock only allow it to absorb halfway.
8) Remove from heat.
9) Add cheese, any remaining butter, and two teaspoons of balsamic vinegar. Stir then cover.
10) Allow it to sit until creamy and thick but not soupy (approximately 2-3 minutes) then serve.
Drizzle with balsamic vinegar and add parmigiano-reggiano as desired.