Butter a 2-quart rectangular baking dish. Sprinkle 2 tablespoons of brown sugar on top of the butter. Set aside.
Cut the slices of bread in half and butter one side of each slice. Sprinkle on chocolate chips. Place in the prepared baking dish.
Whisk together the eggs, cream, sugars, cinnamon, nutmeg, and vanilla in a large bowl until thoroughly combined.
Pour the custard over the bread. Pres down on the bread so it is covered by the liquid. Cover and let it sit in the refrigerator for 30 minutes.
Preheat the oven to 375 degrees F. Place the baking dish in a large pan. Add enough hot water to come halfway up the sides of the dish.
Bake for 40-45 minutes or until the pudding is set and the top is golden brown. Remove the baking dish from the water bath and let it cool slightly on a wire rack.
While the pudding is baking prepare the salted caramel sauce.
Melt butter in a 2 quart saucepan. Whisk in sugar, salt, vanilla extract, and heavy whipping cream.
Bring just to a boil, stirring frequently. Reduce the heat to low and simmer for 15 minutes or until sauce has thickened. Let cool slightly. Serve with warm bread pudding.