Roast Squash: Preheat oven to 425°F (220°C). Brush cut sides and insides of squash and pumpkin with 2 teaspoons olive oil. Season with salt and pepper. Place flesh-side down on a baking sheet. Roast for 50-60 minutes, until fork tender. Let cool slightly, then scoop out flesh.
Sauté Aromatics: While squash roasts, heat remaining olive oil in a large pot or Dutch oven over medium heat. Add onion, carrot, apple, curry powder, and turmeric. Cook for 10-15 minutes, until vegetables are softened.
Simmer Soup: Add the roasted squash and pumpkin flesh, vegetable broth, and apple cider to the pot. Bring to a boil, then reduce heat, cover, and simmer for 20 minutes.
Add Creaminess: Remove from heat. Stir in milk and honey (start with 2 tbsp honey). Add a pinch of salt.
Puree: Use an immersion blender to puree the soup until completely smooth. (Alternatively, carefully puree in batches in a standard blender.)
Season & Serve: Taste and adjust seasoning with salt, pepper, or more honey. Ladle into bowls, garnish with toasted pumpkin seeds, and serve.