You can leave the crouton bread crumbs off of the dish and it will be very low carb. I will say that they really add a ton of flavor and texture to the dish though! If you have someone following a low carb diet, you can compromise by baking the dish without the crumb topping and then baking the crumbs on a foil lined baking sheet next to the dish. Those that want crumbs can spoon them over top and those that don't can pass.