Beat the egg whites with an electric whisk until stiff. Mix the egg yolks, oil, vanilla flavoring, water, and sugar in another bowl. Add the rest of the ingredients for the plain sponge while stirring. Fold in the egg whites.
Divide the cake mix evenly between two deep baking trays lined with baking parchment. Bake for 18 minutes in a convection oven at 340°F.
Let the tray-baked sponges cool. Spread blueberry jelly evenly on top sides of both. Cut both sponges lengthways into five equal strips.
Remove the first strip of sponge and roll it up on itself. Take the second strip and roll it around the first one. Continue until all 10 strips are used.
Prepare the whipped cream. Beat the cream cheese and fold in the whipped cream. Mix sugar and egg yolks in another bowl. Add cocoa powder and flour while stirring. Pour batter into a greased springform pan and bake for 40 minutes at 340°F.
Let the chocolate sponge cool. Cut it in half horizontally. Set one half on a cake plate, spread with cream, place the jelly sponge roll on top. Spread another layer of cream and top with the second half of the chocolate sponge.
Spread cream around the side of the cake. Make grooves in the frosting using a cake comb. Use a piping bag to decorate with frosting stars. Spread the rest of the blueberry jelly in the middle of the cake.