Preheat oven to 400 degrees.
Place prepared squash, carrots, celery, and onions on a baking tray.
Sprinkle with oil. Season with salt, pepper, and thyme.
Roast for 40 minutes, flipping veggies halfway through baking. Veggies should be fork tender when cooked through.
During the last 5 minutes, add the garlic cloves.
Once veggies are cooked, remove from the oven.
In a large Dutch Oven, over medium heat, add the vegetable stock and roasted veggies.
Bring to a boil. Reduce heat to low, simmer for about 5 minutes
Use an immersion blender to blend the soup until smooth. If you do not have an immersion blender. Place half the soup in a blender. place top and cover top with a towel. Hold towel on top and blend until smooth. Do the same with second half of soup.
Soup will be ready to serve. This is an easy make-ahead soup. Can re-heat on the second day. Also perfect as a make-ahead soup. Freezes well, I prefer no longer than 3 months. Defrost in the fridge. Reheat and enjoy.