Preheat the oven to 350 degrees.  Spray a 9” x 13” or similarly sized pan with non-stick spray.  Cut challah into 1 inch cubes and place in the prepared pan.  Sprinkle the chocolate chips evenly over the challah cubes.  Set aside.

In a medium saucepan, place the milk, cream, butter, sugar and espresso and whisk to blend.  Crack the eggs into a separate bowl and mix with a fork to break up the yolks.  Add to the milk mixture and whisk to incorporate.  Heat over a medium low flame, whisking constantly, until the butter is melted.  Remove from the heat and whisk in the vanilla extract.  Carefully pour the mixture over the challah cubes until evenly moistened.  Set aside for 10 minutes until most of the liquid is absorbed.

Bake for 20 to 30 minutes until the center seems set and the top is lightly browned.  Serve warm, cold or at room temperature, ideally with a scoop of vanilla ice cream.