1) Preheat oven to 180C/Gas 4.
2) Follow cake directions as written on cake mix box.
3) Remove from oven and cool cake completely. Meanwhile, in a medium bowl, combine strawberries, cognac and sugar. Let macerate 20 mins. Invert and release cake onto a decorative platter.
4) Whip cream with icing sugar and vanilla at medium-high speed until it reaches stiff peaks. Do not over whip.
5) Make jelly as directed on box. Refrigerate jelly mix but do not let it harden, it should cool to a liquid consistency.
6) Using a straw, poke holes all over the cake. Pour jelly into holes and spread over the top of the cake.
7) Spread layer of macerated strawberries on top of cake. Spread layer of whipped cream on top of the strawberries, making pretty swirls and ripples. Garnish with fresh strawberries. Refrigerate for at least 4 hrs.