In a medium-size, heavy soup pot, melt 2 tablespoons butter over medium-high heat. When it foams, add onion, and cook, stirring, until onion is transparent, about 5 minutes. Reduce the heat to medium, add rice, salt, and pepper, and cook, stirring with a wooden spoon, until well coated, about 1 minute.
Add wine, and simmer gently until the liquid is absorbed, 3 to 5 minutes. Add 1/2 cup chicken stock, stir, and simmer, stirring occasionally, until the liquid is absorbed. Repeat, adding 1/2 cup stock at a time, until the rice is cooked through but still firm, 20 to 25 minutes total.
Add the remaining tablespoon butter and the Parmesan cheese. Mix well, add salt to taste, and serve immediately.