In a 2-qt. saucepan, bring broth to a boil. Reduce heat to a gentle simmer.
Heat a heavy-bottomed 3-qt. saucepan over medium heat until the rim of the pan is hot to the touch. Add in 2 Tbsp. butter and coat the pan.
Add in diced onion and stir occasionally until softened and translucent, about 4 - 6 minutes.
Add the rice and sauté until the rice is coated with butter and has begun to turn opaque, about 2 minutes longer.
Add wine to rice and continue to stir constantly with a wooden spoon. Keep the liquid at a simmer, until most of the liquid is absorbed.
Ladle in 1/2 c. of simmering broth to rice and stir constantly until most of the liquid is absorbed. Continue cooking at a simmer and adding broth, about 1/2 c. at a time. Stir continuously with each addition. Allow all the liquid to be absorbed before adding the next.
Continue this process until the rice is tender and creamy in appearance but still al dente, about 15 - 20 minutes total. (There may be broth left over.)
Stir in the mixed herbs, Parmesan and remaining butter; season with salt and pepper to taste.