1. Preheat the oven to 450 degrees.
2. Prep your ingredients: Peel and roughly chop the butternut squash. Chop the onions, apples, carrots, and celery and layer with the squash in a large roasting pan.
3. Place the whole sprigs of thyme on the chopped apples and veggies and season with salt and pepper. Pour in 2 cups of chicken broth, cover with foil, and place in the oven for 30-60 minutes, until everything is tender.
4. While the apples and veggies are roasting, melt the butter slowly in a small sauté pan, until the milk solids become golden brown. Slice the bread into small cubes and toss in the brown butter. Season with salt and spread onto a cookie sheet; bake in the oven with the roasting pan until the croutons are golden brown, approximately 5-10 minutes.
5. When the apples and vegetables are all fork-tender (approximately 1 hour, it depends on how small you diced everything), remove from the oven and let cool.
6. Next, remove the whole sprigs of thyme and pulse the apples, veggies, tarragon leaves, and ground thyme with the roasting liquids in a food processor until they reach your desired smoothness. Pour into a soup pot with the rest of the chicken stock. Simmer together and season with salt + pepper to taste.
7. Serve warm with sourdough croutons on top.
Tips + Tricks
**The smaller you dice your ingredients, the faster the soup will cook. It makes for more prep, but saves time in the oven.
**If you prefer a chunkier soup, you can roughly blend the soup in the food processor and add a little less chicken broth.