Preheat oven to 400°F (200°C).

Toss potatoes and cauliflower with olive oil, salt, and pepper on a baking sheet.

Roast for 20-25 minutes, or until tender and slightly browned.

In a large pot, combine roasted vegetables, vegetable broth, and garlic powder.

Bring to a boil, then reduce heat and simmer for 10-15 minutes to allow flavors to meld.

Use an immersion blender or transfer to a regular blender to blend until smooth and creamy.

Adjust seasoning to taste.