In a bowl, mix the instant vanilla pudding with milk and whisk until thickened.
In another bowl, whip the heavy cream until soft peaks form.
Add powdered sugar and vanilla extract to the whipped cream and mix gently.
Fold the whipped cream into the pudding mixture until well combined.
Line a rectangular dish with a layer of graham crackers.
Spread half of the pudding mixture over the graham crackers.
Add another layer of graham crackers on top of the pudding.
Spread the remaining pudding mixture over this layer of graham crackers.
Top with a final layer of graham crackers, covering the pudding.
In a saucepan, melt chocolate chips and butter over low heat, stirring until smooth.
Pour the chocolate glaze over the top layer of graham crackers, spreading evenly.
Refrigerate for at least 4 hours or overnight to set.