Preheat oven to 400°. Line a 17½×11½-inch jelly roll pan with parchment paper, and spray with cooking spray.
In the bowl of a stand mixer, beat egg whites at high speed until stiff but not dry. Transfer to a small bowl; set aside.
In the same bowl of stand mixer, beat egg yolks at medium speed until light. Gradually add sugar and vanilla, and mix well. Sift together flour, baking powder, and salt. Add flour mixture to egg yolk mixture, beating until blended. Fold egg whites into egg yolk mixture, and pour batter into prepared pan. Bake until cake is golden and springs back when lightly touched in the center, 8 to 10 minutes.
Loosen edges of cake, and invert cake onto a clean tea towel dusted with confectioners’ sugar. Gently remove parchment paper. Trim ¼ inch of hard crust off each long side of cake. Starting at 1 long side, roll up cake and towel together. Let cool on a wire rack, seam side down, for 10 to 15 minutes.
Once cake has cooled, gently unroll. Spread White Chocolate Mousse onto cake. Reroll cake without towel into a log shape, and dust with confectioners’ sugar. Refrigerate until ready to serve.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/white-chocolate-roulade-recipe/