Stale the bread: leave sliced or cubed bread out for 2-3 hours or until slightly dried. Alternatively, you can toast the bread lightly in a low-heat oven for a few minutes until dried out.
Place cubed, staled bread in a greased 9×13” baking dish.
In a large bowl, whisk together the melted butter, ¾ cup lemon juice, salt, sugar, cornmeal, cornstarch, and eggs until smooth.
Pour mixture over cubed bread in baking dish. Press down on the bread cubes to make sure they are completely coated with the filling and are evenly distributed in the pan.
Cover loosely with foil and bake at 350 degrees for 30 minutes. Remove foil and continue baking for 15 minutes.
Prepare Lemon Whipped Cream: Use an electric mixer to beat heavy cream until it begins to thicken. Gradually mix in sugar and 1 tbsp. lemon juice. Beat until soft peaks form. Fold in lemon zest; cover and refrigerate until ready to use.
Top Lemon Chess Bread Pudding with the Lemon Whipped Cream and dust with additional powdered sugar, if desired. Serve warm or room temperature.