Start by thinly slicing your onions; aim for even slices to ensure they cook uniformly. Gather all other ingredients so you're ready for action.

In a large pot over medium heat, melt butter until foamy. Add onions and cook slowly until golden brown and soft—about 25 minutes! Stir occasionally.

Toss in your beef chuck roast along with salt and pepper. Sear each side until browned—this step locks in flavor!

Next, add your beef broth along with sherry or red wine. Bring everything to a gentle boil before reducing heat to low.

Let your soup simmer for about 90 minutes until the beef is fork-tender.

Ladle hot soup into oven-safe bowls, place toasted baguette slices atop each serving, then generously sprinkle Gruyère cheese on top.

Preheat your broiler and place bowls under it for about 3-5 minutes until cheese bubbles and turns golden brown—watch closely!