Place raw cashews in a small bowl and cover with hot water. Let them soak for at least 15 minutes while you prepare other ingredients. Drain well before using. (If you have a high-speed blender, soaking may not be strictly necessary, but it helps ensure a super smooth texture.)

Heat olive oil in a large pot or Dutch oven over medium heat. Add chopped onion and sauté for 5-7 minutes, until softened and translucent. Add minced garlic and sauté for another minute until fragrant.

Stir in the roughly chopped broccoli florets and tender stems. Add vegetable broth, dried thyme, black pepper, and salt. Bring to a boil, then reduce heat, cover, and simmer for 10-12 minutes, or until the broccoli is very tender.

Remove the pot from heat. Add the soaked and drained cashews, plant milk, nutritional yeast (if using), and lemon juice directly to the pot. Use an immersion blender to blend the soup until completely smooth and creamy. Be careful as the soup is hot.

Carefully transfer the cooked soup mixture to a high-speed blender. Add the soaked and drained cashews, plant milk, nutritional yeast (if using), and lemon juice. Secure the lid and blend until completely smooth. Pour the blended mixture back into the pot and stir well to combine.

Return the pot to low heat and gently warm the soup through if needed, stirring constantly. Taste and adjust seasonings (salt, pepper, or lemon juice) as desired.

Serve hot, garnished with a sprinkle of fresh parsley, croutons, or a swirl of vegan cream if desired.