Lightly grease a 15x10x1-inch jelly-roll pan. Line bottom with waxed paper; grease paper. Set pan aside. Stir together flour and baking powder; set aside. Separate eggs; cover whites and set aside.
Beat egg yolks and vanilla in a small mixing bowl with an electric mixer on high speed until mixture thickens (about 5 minutes). Slowly add 3 tablespoons of the granulated sugar; beat on high speed until sugar is dissolved.
Wash beaters. In a clean small bowl, beat egg whites on medium speed until soft peaks form (tips curl). Gradually add the remaining granulated sugar, beating until stiff peaks form (tips stand straight).
Fold the egg yolk mixture into beaten egg whites. Sprinkle flour mixture over egg mixture; fold in gently just until combined. Spread batter evenly in the prepared pan.
Bake in the preheated oven for 8 to 10 minutes or until cake springs back when lightly touched. Immediately loosen edges of cake from pan with a narrow spatula and turn cake out onto a towel sprinkled with powdered sugar. Carefully peel off waxed paper. Roll up towel and cake, jelly-roll style, starting from one of the short sides. Cool on a wire rack for at least 1 hour.
Carefully unroll cake and remove towel. Cut cake in half lengthwise. Cut each half crosswise into thirds. For each jelly roll, spread one cake square with 1 to 2 tablespoons fruit preserves or other filling to within 1/2-inch of edges. Roll up the square and carefully slice in half crosswise. If desired, sprinkle tops of rolls with additional powdered sugar. Makes 12 miniature jelly rolls.