Prepare cake mix as directed. Fold chopped strawberries into batter, then pour batter into two 9-inch-round cake pans. Bake as directed. Let cakes cool as directed. Let cakes cool on a wire rack. Transfer one cake layer to a serving plate.
In a medium bowl, whisk heavy cream until soft peaks form. Add sugar and continue whisking until stiff peaks form. Spread half of the whipped cream on one cake layer. Top cake with remaining layer, spread on remaining whipped cream, and decorate with