1. Bring stock to a simmer in a saucepan (do not boil). Keep warm over low heat.
2. Heat a Dutch oven over medium heat. Add oil to pan; swirl to coat. Add onion; cook 5 minutes, stirring occasionally. Add rice, salt, and saffron; cook 1 minute, stirring frequently. Add wine; cook 2 minutes or until liquid is absorbed, stirring frequently. Stir in 1 1/2 cups stock; cook 4 minutes or until liquid is nearly absorbed, stirring constantly. Add remaining stock, 3/4 cup at a time, stirring nearly constantly until each portion is absorbed before adding the next (about 22 minutes total); reserve 1/3 cup stock at last addition. Remove pan from heat. Stir in reserved 1/3 cup stock, butter, pepper, and cheese. Top with parsley.