Prepare the Sponge Cake: Preheat the oven to 375°F (190°C) and line a half-sheet pan with parchment paper. Whip the egg whites until soft peaks form, then gradually add half of the sugar and beat until stiff peaks form. In another bowl, beat the egg yolks with the remaining sugar and vanilla until thick. Gently fold the yolk mixture into the whites, then sift in the cake flour and fold until just combined. Spread the batter evenly into the pan and bake for 10-12 minutes.
Roll the Cake: While the cake is warm, dust a clean kitchen towel with powdered sugar. Invert the cake onto the towel, remove the parchment paper, and roll the cake up with the towel to cool completely.
Make the Filling: Lightly mash half of the raspberries in a bowl. In another bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form. Gently fold in the mashed raspberries.
Assemble the Cake: Unroll the cooled sponge cake, spread a thin layer of raspberry preserves, followed by the whipped cream filling. Scatter the remaining whole raspberries over the cream. Carefully re-roll the cake without the towel.
Chill & Serve: Transfer the cake to a platter, dust with powdered sugar, and garnish with fresh raspberries if desired. Slice and serve chilled.