Heat olive oil in a large pot over medium heat. Add chopped onion and cook until softened, about 5 minutes.

Add cubed potatoes and vegetable broth to the pot. Bring to a boil, then reduce heat and simmer for 15-20 minutes, or until potatoes are tender.

Carefully transfer the soup to a blender (or use an immersion blender) and blend until smooth and creamy.

Return the soup to the pot and stir in plant-based milk, garlic powder, and black pepper. Heat through gently.

Season with salt to taste. Serve hot.