Whisk together the milk and slightly cooled melted butter in a separate bowl. Pour the milk and butter mixture evenly over the chocolate cake mix and pudding in the baking dish. Whisk lightly to combine (this is optional).
2 ½ cups whole milk
Sprinkle chocolate chips evenly over the top then bake for 35 to 45 minutes, or until the cake is set and the edges are lightly browned. Cool on a wire rack for 10 minutes before serving warm with whipped cream or ice cream.