Paris: Crockpot French Onion Soup

I saw this recipe for French Onion Soup....in a crockpot at Smashed Peas, and I knew I had to try it out.  First, I'm always looking for great recipes from the crockpot...because they are easy....AND....I had this spectacular French Onion Soup in France a few years ago, and I've been seeking out this memory from this point forward.  Usually French Onion Soup is relatively high mainatance, so I was skeptical at the ease of this soup, BUT....it was my favorite to date!  I'm keeping it for sure!  I halved the recipe, which made enough for 4, but this is the full list of ingredients. 
Crockpot French Onion Soup Ingredients
3 onions, sliced (I used a mix of white and yellow), 3 T. butter, 3 T.  flour, 1 T. Worcestershire Sauce, 1 t. sugar, 1/2 t. pepper, 2 32-oz cartons of beef broth
Baget, Swiss or Gruyere cheese (I just bought slices from the deli). 
Crockpot French Onion Soup Instructions
Melt butter in the bottom of a crockpot. 

 Add onions, toss, and then cook covered for 45 minutes. 

 This carmalizes the onions, mine never looked as brown as they usually do when you carmelize onions on the stove, but it still tasted great. 

 Add the rest of the ingredients (except the cheese and bread).  Cook on low for 6-8 hours, or high for 3-4 hours.  I actually added the ingredients, but it in the fridge, and then pulled it out in the morning before heading to work and let it cook all day. 

I sliced the bread then, added the cheese to the top and placed these in bowls of soup in the oven and broiled it on high for a few minutes (until cheese is melted).  You can also just put the bread and cheese on a cookie sheet and toast them up until the cheese is melted at about 300 degrees for a few minutes.