Preheat oven to 350°F (175°C). Grease a 10x15 inch jelly roll pan, line with parchment paper (with overhang on short sides), and grease the parchment.

Make Meringue: In a clean bowl, beat egg whites until foamy. Add cream of tartar. Gradually add 1/4 cup sugar, beating to stiff, glossy peaks. Set aside.

Make Yolk Base: In another bowl, beat yolks with remaining 1/2 cup sugar until thick, pale, and ribbon-like (2-3 mins). Beat in oil, buttermilk, and vanilla.

Combine Dry Ingredients: Whisk flour, cornstarch, raspberry powder, baking powder, and salt. Sift into yolk mixture. Fold until just combined.

Fold in Meringue: Gently fold 1/3 of meringue into batter to lighten. Fold in remaining meringue in two additions until no white streaks remain.

Bake: Spread batter evenly in pan. Bake 10-12 min until top springs back. Do not overbake.

Roll While Hot: Dust a clean towel with powdered sugar. Invert hot cake onto towel, peel off parchment. Roll cake up tightly with towel inside. Cool completely on a wire rack (1 hr).

Make Filling: Cook 1 cup raspberries with 2 tbsp sugar until broken down, 5-7 min. Sieve to remove seeds; cool. Whip heavy cream to soft peaks. In another bowl, beat mascarpone, jam, powdered sugar, and cooled compote until smooth. Fold in whipped cream. Chill.

Fill & Re-Roll: Unroll cooled cake. Spread filling evenly, leaving a 1/2-inch border. Re-roll cake (without towel). Place seam-side down on platter. Refrigerate 2+ hours.

Make Glaze: Place chopped chocolate in bowl. Heat 1/2 cup cream until simmering. Pour over chocolate, wait 1 min, then whisk smooth. Whisk in butter. Cool 10-15 min until thickened.

Glaze & Serve: Place chilled cake on wire rack over baking sheet. Pour glaze over top, smoothing sides. Decorate with berries and chocolate curls. Let set 10 min. Slice with a sharp knife.