For the ice cream sauce: Slowly heat 3/4 cup melted ice cream in a small saucepan over medium-low heat. Mix together the cornstarch and remaining 1/4 cup melted ice cream in a small bowl until smooth. Whisk the cornstarch mixture into the saucepan and bring to a simmer. Cook, stirring, until slightly thickened, about 1 minute. Set aside and cool completely.
For the strawberries and whipped cream: Toss the strawberries with 1/2 cup sugar in large bowl. Let stand, tossing occasionally, until the strawberries release their juice and a syrup forms, about 1 hour.
Using an electric hand mixer, beat the cream, vanilla extract and remaining 3 tablespoons sugar in another large bowl until stiff peaks form. Keep refrigerated until ready to serve.
To assemble: Cut the shortcakes or mini pound cakes in half. Spoon 2 tablespoons of the ice cream sauce onto each plate. Place a shortcake bottom on top of the sauce. Top each generously with strawberries and whipped cream and cover with a shortcake top. Dust with confectioners' sugar and serve.