Preparation: Preheat your oven to 400°F (200°C). Soak the cashews in water for at least 2 hours, then drain and set aside.

Roasting Broccoli: Place the broccoli florets on a baking sheet, drizzle with olive oil, and roast in the oven for about 20 minutes, or until tender and slightly browned.

Sautéing Vegetables: In a large pot, heat the remaining olive oil over medium heat. Add the diced onion and carrot, sautéing until softened, about 5 minutes. Add the garlic and sauté for another minute.

Blending: Add the roasted broccoli, soaked cashews, vegetable broth, nutritional yeast, and a pinch of turmeric (if using) to the pot. Bring to a boil, then reduce the heat and let it simmer for 10 minutes.

Pureeing: Using an immersion blender, blend the soup until smooth. Alternatively, you can transfer the soup in batches to a high-powered blender.

Final Touches: Return the soup to the pot if using a blender, stir in the lemon juice, and season with salt and pepper to taste. If the soup is too thick, add more vegetable broth until desired consistency is reached.

Serving: Serve hot, garnished with roasted nuts if desired.