Slow-Cooker French Onion Soup

I had to read the directions a couple of times because my brain was saying “8 hours on HIGH HEAT??!” I was so looking forward to this as my first time making this soup and had such high hopes…like it’s in a slow cooker…how could I screw it up?😉
So pushing back my instincts, I followed the recipe except I had to use dried thyme instead of fresh, but I went easy on it. It was smelling sooo good after even just an hour! But at about the 2.5 hour mark, my hubby said “something is burning”. I just responded that the onions had to cook on high for 8 hours and again ignoring my instincts. At hour 3 I couldn’t take it anymore and had to take a peek. The onions on the sides of the slow cooker were indeed burned black (not brown, but black!) and stuck to the sides (I did use cooking spray before I started everything as I do that with every recipe). Finally at hour 4 I decided to go ahead and add my liquids and turn the heat down to around 325. Another hour of cooking and I just had to turn it off. I sampled it and while the broth had such possibilities, the overwhelming taste of burned/charred food was just too much. I feel like I wasted so much time and wasted food in this. I might attempt again (mostly out of determination!) but I will tweak the recipe, starting with a lower temp and making sure to stir the onions around in the butter/oil/herb mixture every hour if I can.
Did anyone else have an issue with your onions burning?

I ABSOLUTELY ADORED this recipe!! IMHO (in my humble opinion), this recipe is the BEST I've tried!! It's so easy, the onions are gorgeously caramelized and the broth is wonderful!! I've made the recipe two more times just for the caramelized onions...I've found so many ways to use them! I highly recommend to definitely use the fresh thyme, the smashed garlic, and the sherry! I think the sherry ads a bit of brightness or even an umami flavor?! Oh, I did not use the red onions, I just used a combination of yellow and sweet and definitely the Gruyere!

I thought the broth amount was fine. When I started the onions in the slow cooker, I also cut 3/4" slices of French bread and laid them out to dry. By the time the soup was ready later in the day, they had the "day old" crustiness, which was perfect for soaking up the soup without becoming mushy. I also grated my gouda and swiss fresh from blocks of cheese, which was suuuuuper tasty. I thought it was a very good recipe. It still misses that last bit of "zing" that would make it equal to a restaurant, but it was better than I hoped for from home made.

Really good! I would suggest adding at least two more cups of broth than the recipe suggested.

Bland and not enough broth.

Great recipe & easy to make! I made this for lunch, so I cooked the onions overnight. I've read on other sites, that people cooked the onions in their garage. Your house will definitely smell like onions. I also added 8 cups beef broth, 4 was definitely not enough, and 1/2 cup sherry. I also added 2 tsp. balsamic vinegar. I brought it to work to share and everyone loved it. Definitely a keeper!! Pros: so easy in the slow cooker, great tasting Cons: not enough broth