Preheat oven to 350°F. Lightly spray pans with vegetable pan spray.
In small bowl, combine flour, baking powder and salt. In medium bowl, combine melted butter, sugar, egg, sour cream and vanilla extract; beat thoroughly. Gently fold in flour mixture. Divide batter evenly between three mini loaf pans.
Bake 28-32 minutes or until toothpick inserted in center comes out clean. Cool cakes in pans on cooling rack 5 minutes; remove from pans. Cool completely. Dust with confectioners' sugar, if desired.