In a large pot over medium-high heat, melt the olive oil and butter. Add the onions and garlic to the pot, stir and cook until the onions have turned translucent. Takes about 5-8 minutes.
Add chopped thyme to the pot. Reduce heat to low, still cooking onions. Make sure to stir occasionally so that nothing sticks to the bottom on the pot. Continue to do so for about 30 minutes or the onions are a light brown.
Once the onions are golden brown. Turn the high up to medium and add in the red wine. Cook for 3-5 minutes, stirring to mix and reduce the wine.
In a bowl, large glass measuring cup, or the pot. Combine the beef concentrate (better than bouillon) and the water. Add it to the pot. Season with salt and pepper.
Preheat the oven to 350 degrees F. Taking a medium sized baking sheet and line it with parchment paper. Make sure to cube your gluten free baguette. Place cubed bread in a large bowl.
In a small bowl, mix together olive oil, thyme, rosemary, salt and garlic. Pour the mixture over the cubed bread and toss to coat.
Take your parchment lined baking sheet and spread out the coated cubes evenly. Sprinkle over the parmesan cheese, making sure to evenly distribute it on the brad cubes. Use your hands to coat the bread if necessary.
Pop the baking sheet in the oven for 20-30 minutes, or until golden brown. Flipping the croutons once or twice while cooking.
When done, remove from heat and let cool.
Finishing the Soup and Plating
When your croutons are done in the oven. Preheat the broiler on high (you have have an option).
Use oven safe bowls and place them on a baking sheet. Evenly ladle in the french onion soup to each bowl. Drop in a handful of the parmesan-thyme croutons. Sprinkle on the gruyere cheese and place a sprig of thyme on top.
Carefully place the bowls on the baking sheet into the oven under the broiler for 1 minute, or until the cheese is bubbly and golden brown. Keep an eye on it, so that it doesn’t burn. Once done, remove from oven and serve immediately.