Line the bottom of a 9-inch springform pan with a parchment paper circle. Wrap the outside of the pan with a double layer of plastic wrap to prevent leaks.

In a small bowl, combine the 1 ½ cups cookie crumbs (filling removed) with the melted butter. Press firmly into the bottom of the prepared pan. Place in the freezer while you make the filling.

In a large chilled bowl, beat the heavy cream on medium-high speed until stiff peaks form (about 3-4 minutes). Set aside.

In another large bowl, whisk together the cold sweetened condensed milk, vanilla extract, and salt until smooth.

Gently fold one-third of the whipped cream into the condensed milk mixture to lighten it. Then fold in the remaining whipped cream until no white streaks remain. Fold in the 1 ½ cups crushed cookies (with filling).

Pour the filling over the frozen crust. Smooth the top with an offset spatula. Drizzle the warm fudge sauce over the top and swirl with a knife.

Cover the pan with plastic wrap and freeze for at least 6 hours, or overnight, until fully firm.

To serve, run a warm knife around the edge of the pan, release the springform, and remove the parchment. Let the cake sit at room temperature for 5 minutes before slicing. Use a sharp knife dipped in hot water and wiped dry between cuts.