Start by peeling and finely chopping the onions. This step might bring a tear to your eye, but trust me, it's worth it. The onions are the star of this show, and their sweetness will shine through once they’re cooked.

In a large pot, heat the olive oil and butter over medium heat. Once the butter melts, add the chopped onions. Cook them slowly, stirring occasionally, until they’re golden brown and caramelized. This should take about 15-20 minutes. Your kitchen will start smelling heavenly.

Once caramelized, pour in the beef broth. If time allows, you can combine the beef stock cubes with water for a rich flavor. Stir it well, and bring the mixture to a light simmer.

Now, it’s time to add the Knorr French onion soup mix. This is where the magic happens. Stir it into the broth, mixing thoroughly. Let it simmer for about 5-10 minutes. The heat allows the flavors to meld beautifully.

While the soup simmers, preheat your oven to 375°F (190°C). Place the slices of baguette on a baking sheet and toast them for about 10 minutes, or until they are golden and crispy. This will give you that delicious crust for your soup.

Ladle the hot soup into bowls. Top each serving with a sprinkle of grated cheese and a slice of toasted bread. For an extra touch, finish with thyme leaves and cracked black pepper. Enjoy the warmth!