Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
In a large mixing bowl, combine the cake mix, eggs, vegetable oil, and milk. Beat with an electric mixer on medium speed for about 2 minutes until well combined and smooth.
Gently fold in the crushed chocolate sandwich cookies, being careful not to overmix.
Pour the batter into the prepared baking pan and spread evenly. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cake to cool for about 10 minutes in the pan, then use the handle of a wooden spoon to poke holes all over the surface of the cake. Make sure to poke at least 24 holes.
In a separate bowl, whisk together the sweetened condensed milk and about 1/2 cup of the reserved crushed cookies until well combined. Pour this mixture evenly over the cake, ensuring it seeps into the holes.
Let the cake cool completely, then refrigerate for at least 2 hours, allowing the flavors to meld.
For the frosting, whip the heavy cream in a mixing bowl until soft peaks form. Gradually add in the powdered sugar and vanilla extract, continuing to beat until stiff peaks are achieved.
Spread the whipped cream frosting evenly over the chilled cake. Top with extra crushed chocolate sandwich cookies for decoration.
Slice and serve chilled, indulging in the creamy, cookie-filled layers!
Notes
Chill the cake for at least 2 hours for the best flavor.