Preheat your oven according to the cake mix instructions, usually 350°F (175°C). Line a cupcake tin with liners. Prepare the cake mix as directed on the box, then fill each cupcake liner about two-thirds full. Bake according to the package timing, usually around 18–22 minutes, until the tops are golden and a toothpick inserted into the center comes out clean. Let the cupcakes cool completely on a wire rack before moving to the next step.

In a medium bowl, whisk together the instant vanilla pudding mix and cold milk until smooth and thickened, about 5 minutes. Set aside.

Using a small knife or cupcake corer, carefully cut a small hole (about 1 inch deep) into the center of each cupcake. Spoon or pipe the vanilla pudding into the holes until they’re full but not overflowing.

Heat the heavy cream in a small saucepan over medium heat until it just begins to simmer—watch closely to avoid boiling. Pour the hot cream over the semi-sweet chocolate chips in a heat-safe bowl. Let sit for 2 minutes, then stir gently until smooth and glossy.

Spoon the ganache over each filled cupcake, allowing it to drip slightly down the sides for that signature look. Let the ganache set at room temperature or in the fridge for quicker results before serving.