PRINTABLE RECIPE & NUTRITION INFO: https://www.thereciperebel.com/slow-cooker-french-onion-soup/
Ingredients
▢1 tablespoon oil
▢4 large yellow onions
▢¼ cup salted butter
▢1 tablespoon brown sugar
▢1½ teaspoons salt
▢½ teaspoon dried thyme
▢¼ teaspoon pepper
▢⅛ teaspoon red chili flakes
▢5 cups low sodium beef broth
▢⅔ cup dry white wine (or sub additional broth)
▢1 bay leaf
▢4 thick slices French bread or 8 slices baguette
▢2 tablespoons salted butter
▢1 cup shredded cheese (Gruyere, Mozzarella, Gouda, Swiss, Parmesan, Asiago, etc. — a combination if possible)
Instructions
Heat the oil in a large skillet over medium-high heat.
Slice the onions thinly (I like to cut shorter slices — from a quarter onion rather than a half — so they fit more nicely on the soup) and add to the skillet.
Cook and stir until softened and starting to brown, about 10 minutes.
Add the butter, brown sugar, salt, thyme, pepper and red chili flakes. Cook and stir until beginning to caramelize, about 5 minutes.
Place the onions in a 3-4 quart slow cooker and stir in the broth, white wine (or sub broth) and bay leaf. Cook on low for 6-8 hours.
Just before serving, preheat the oven to 425℉. Lightly butter both sides of the bread slices, and place on a parchment lined baking sheet.
Place in the oven and toast for 3-4 minutes, then flip and top each with cheese. I like to use 2-3 cheeses for the best flavor, but the kinds you use are very customizable. If adding hard cheeses, I recommend only a small sprinkling of those along with a good melting cheese.
Bake for 3-4 minutes, until toasted and golden.
Taste soup and adjust seasonings as desired. Ladle into four bowls and top with toasted bread slices. Serve.