In a medium bowl, combine the sliced strawberries, granulated sugar, and vanilla extract. Toss well and let sit for about 15 minutes to macerate the strawberries.
In a 9-inch springform pan, layer half of the crumbled shortcake or sponge cake evenly on the bottom.
Spread half of the softened vanilla ice cream over the shortcake layer, smoothing it out with a spatula.
Spoon half of the macerated strawberries over the vanilla ice cream layer.
Add the remaining crumbled shortcake or sponge cake on top of the strawberries.
Spread the softened strawberry ice cream over the shortcake layer, smoothing it out evenly.
Top with the remaining macerated strawberries and finish with a layer of whipped cream, spreading it evenly over the top.
Cover the cake with plastic wrap and freeze for at least 4 hours or until firm.
Before serving, let the cake sit at room temperature for about 10 minutes to soften slightly. Remove the sides of the springform pan and garnish with fresh strawberries if desired.