Heat a dry, small saucepan over high heat until hot. Add the pasta, and cook, stirring, until deep golden brown, about 1 1/2 minutes. Add butter; cook, stirring occasionally, until melted. Stir in onion and salt; cook, stirring occasionally, until onion is translucent, about 2 minutes. Stir in rice, and cook, stirring, 1 minute.
Add stock to pan; bring to a boil. Reduce heat and simmer, covered, 15 minutes. Remove from heat; let pilaf stand, covered, 10 minutes. Fluff with a fork before serving.