Heat olive oil in a pot with a heavy bottom over medium heat. Chop the onion and add to the pot until soft 5-7 min.
Meanwhile wash and half the squash and apple. Remove the seeds and chop them into 2 cm (1 inch) cubes.
Add to the onion and stir. Roast for 2-3 min. Pour enough water to cover the vegetables by 5 cm (2 inches). Bring to boil over high heat. Lower heat to medium and simmer with the lid half on until the squash is fork tender. (i.e. You can pierce it with a fork easily without it falling apart)
Let the soup cool down and using a blender pure it to desired consistency. Season to taste. Serve in hot bowls and garnish with olive oil and fresh thyme springs.