In a large mixing bowl, combine your cake mix, eggs, and vegetable oil. Use a hand mixer to blend the ingredients on medium speed for about 1-2 minutes until the mixture is smooth and well-combined.

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper. Drop rounded tablespoons of dough onto the prepared baking sheet, ensuring they are spaced apart. Bake for 10-12 minutes or until the edges are lightly golden.

While the cookies cool, prepare the vanilla pudding filling by whisking together the vanilla pudding mix and milk until thick, about 2 minutes. Cover and refrigerate for 10-15 minutes.

Once the cookies are completely cooled, spread a tablespoon of the pudding filling on the flat side of one cookie and top it with another cookie, pressing gently to form a sandwich.

In a small saucepan, heat heavy cream until steaming, then pour over chocolate chips and stir until smooth to prepare the ganache.

Drizzle the ganache over the assembled cookie sandwiches and let it set at room temperature for about 15-20 minutes before serving.