I'm not so sure that would be in my future, but I did crack out a mandoline that I had received as a gift (and never used) and it did make really quick work of slicing up all of those onions. Yes mom, I did use the safety shield holder, so you can relax. I liked the control compared to a food processor where I can never get things uniformly sliced or chopped, but I'm not giving up my knives just yet. I'm going to be using it a whole lot more in the future!
The onions came out amazing and the French onion soup was top notch. I did learn that this is a dish that you start at night and let it go while you sleep. Thanks again to you and @Mikiesboy for the recipe!