Grease and flour two 9-inch round cake pans. In a large mixing bowl, combine the cake mix, eggs, and oil, along with the amount of water called for by the package directions. Beat until well combined. Divide the batter between the pans. Place in oven and bake until a toothpick inserted into the center of the cakes comes out clean, about 30 minutes. Let the cakes cool for at least 10 minutes before removing them from the pans. Cool completely before assembling the shortcake.
Meanwhile, sprinkle 1/2 cup of the sugar over the strawberries. Set aside at room temperature until the berries release their juices, about 30 minutes. About 15 minutes before serving, combine the cream and the remaining sugar in a medium bowl and whip by hand or with an electric mixer until stiff peaks form. Place one of the cake layers on a serving platter. Pile on half the strawberries and half the whipped cream. Top with the remaining layer, the rest of the whipped cream, and the remaining strawberries. Serve immediately.