In a bowl, use a hand mixer or whisk to beat the cold heavy whipping cream until stiff peaks form. The cream should hold its shape when the bowl is turned upside down.
In another bowl, combine the dry cake mix, milk, sweetened condensed milk, and vanilla extract. Whisk until there are no lumps.
Gradually add the cake mixture to the whipped cream, gently folding them together to avoid deflating the air.
Prepare a 9-inch round cake pan or a springform pan. Dip vanilla cookies into milk and arrange them in a single layer at the bottom of the pan. Break up additional cookies to fill any gaps.
Pour half of the ice cream mixture over the cookies, then sprinkle 1/4 cup of sprinkles on top. Repeat the layers by adding another layer of dipped cookies and the remaining ice cream mixture.
Decorate the ice cream cake with Cool Whip and additional sprinkles. Use a piping bag to pipe the Cool Whip and get creative with the decoration.
Place the cake on a level surface in the freezer and freeze for at least 6 hours. For best results, make the cake a day ahead.
Before serving, let the ice cream cake sit at room temperature for 10-15 minutes to make it easier to cut. Use a sharp, large chef knife to slice the cake into portions. Enjoy! 🙂