Preheat Oven and Prepare Pan: Preheat oven to 375°F (190°C). Line a 10×15-inch jelly roll pan with parchment paper and lightly grease.

Beat Egg Yolks and Sugar: In a large bowl, beat egg yolks with ½ cup sugar until thick and pale. Stir in vanilla extract.

Combine Dry Ingredients: In another bowl, whisk flour, baking powder, and salt.

Fold Dry Ingredients: Gently fold dry ingredients into the yolk mixture until combined.

Beat Egg Whites: In a clean bowl, beat egg whites until soft peaks form. Gradually add remaining ¼ cup sugar and beat until stiff peaks form.

Fold Egg Whites: Carefully fold egg whites into batter in two additions, keeping as much air as possible.

Bake Cake: Pour batter into pan and spread evenly. Bake 12-15 minutes until cake springs back when touched.

Roll Cake: While warm, invert cake onto a towel dusted with powdered sugar. Remove parchment. Roll cake and towel from a short edge; cool completely.

Prepare Filling: Beat heavy cream with powdered sugar until stiff peaks form. Fold in raspberry jam.

Unroll and Fill: Unroll cooled cake and spread raspberry cream evenly.

Re-Roll and Chill: Roll cake back up without towel. Wrap in plastic wrap and refrigerate at least 2 hours.

Serve: Dust with powdered sugar, garnish with fresh raspberries if desired, slice, and serve chilled.