While the crockpot does most of the heavy lifting, caramelizing the onions is where the magic begins. Heat the butter and olive oil in a large skillet over medium heat.

Add the sliced onions and sugar, stirring occasionally until the onions turn a deep golden brown. This can take about 25-30 minutes. Be patient, as this step lays the foundation for your soup’s rich flavor.

Transfer the caramelized onions to your crockpot. Add the minced garlic, beef broth, white wine, Worcestershire sauce, and dried thyme. Salt and pepper can be added according to taste. Give everything a good stir to combine.

Set your crockpot to low and cook for 6-8 hours. Alternatively, you can cook on high for 4 hours if you’re in a hurry. Slow cooking allows the onions to melt into the broth, creating a beautifully layered flavor.

While the soup is nearing the end of its cooking time, slice your baguette and toast the slices in the oven until they’re crisp and golden.

Ladle the hot soup into oven-safe bowls. Top each bowl with a toasted baguette slice, and generously sprinkle shredded Gruyère cheese over the top.

Place the bowls on a baking sheet and broil in the oven for 1-2 minutes, just until the cheese is bubbly and slightly browned. Watch closely to avoid burning.

Carefully remove the bowls from the oven (they’ll be hot!), and serve your Crockpot French Onion Soup immediately. Pair with a side salad or crusty bread for a complete meal.