Heat a large pot over medium heat and add a tablespoon of olive oil. Once shimmering, add the chopped onion and sauté until translucent and fragrant, about 5 minutes, stirring occasionally.
Add the minced garlic and cook for another minute, until it releases a savory aroma and becomes slightly fragrant.
Stir in the broccoli florets and cook for 2-3 minutes, allowing them to become vibrant green and slightly tender.
Pour in the vegetable broth, then bring the mixture to a gentle simmer. Cover and cook until the broccoli is tender, about 15 minutes, filling your kitchen with a fresh, green aroma.
While the soup simmers, drain the soaked cashews and transfer them to a blender. Add 1/2 cup of water and blend until completely smooth and creamy, creating a silky cashew base.
Once the broccoli is tender, remove the pot from heat. Use an immersion blender to puree part of the soup, blending until smooth but leaving some chunks for texture.
Stir in the cashew cream, nutritional yeast, lemon juice, salt, and pepper. Mix well and taste, adjusting seasonings as needed. The soup will thicken and develop a rich, cheesy aroma.
Return the pot to low heat and cook for another 5 minutes, stirring occasionally, until thoroughly heated and flavors meld.
Taste again and adjust salt, pepper, or lemon juice if needed. Once satisfied, remove from heat and let sit for a few minutes to allow flavors to deepen.
Serve hot, garnished with extra nutritional yeast or fresh herbs if desired. Enjoy the creamy, cheesy aroma and vibrant green color of this comforting vegan soup!