Preheat the oven to 400 degrees F. Halve the squash lengthwise and scoop out the seeds. Place the halves cut-side down on a parchment-lined baking sheet and roast for 40 to 45 minutes, until a knife slides easily into the thickest part. Let cool until easy to handle, then scoop the flesh into a bowl and discard the skin.

Heat the olive oil in a large soup pot or Dutch oven over medium heat. Add the onion and saute for 8 to 10 minutes, stirring occasionally, until softened and golden. Add the garlic and cook for 1 minute, until fragrant.

Add the roasted squash, diced apple, vegetable broth, ginger, cumin, curry powder, and nutmeg. Bring to a simmer, then cook uncovered for 15 to 20 minutes, until the apples are very soft.

Puree the soup directly in the pot with an immersion blender until completely smooth. (No immersion blender? Carefully transfer the soup to a stand blender in batches, venting the lid to let steam escape, then return it to the pot.)

Stir in the non-dairy milk, adding a bit more if the soup is thicker than you would like. Warm through over low heat for about 5 minutes, then season with salt and pepper to taste.

Ladle into bowls and garnish with fresh thyme leaves and a side of crusty bread or croutons. Serve hot.