Heat 2 tablespoons of olive oil and 1 tablespoon of butter in a large pot over medium heat until the butter melts and foams.

Add 1 diced onion, 2 sliced leeks, and 2 chopped garlic cloves to the pot. Sauté until soft and fragrant, about 5 minutes.

Stir in 4 cups of cubed sweet potatoes and 1 teaspoon of cumin powder. Cook for 3 minutes, stirring frequently.

Pour in 4 cups of chicken or vegetable stock, and season with salt and black pepper. Simmer for 20 minutes until sweet potatoes are fork-tender.

Blend the soup until smooth and creamy using a stick blender.

Stir in 1/2 cup of cream or an additional tablespoon of butter for extra richness. Adjust seasoning if needed.

Ladle the soup into bowls, drizzle with olive oil, and garnish with yogurt, pistachios, or crispy flatbread.