In a large Dutch oven, heat 2 tablespoons of olive oil over medium-low heat. Add the chopped yellow onion and a pinch of kosher salt, stirring occasionally for about 3 minutes until the onions become translucent and fragrant.

Stir in 3 cups of diced sweet potatoes, 2 cups of sliced carrots, and 1 diced tart apple. Increase the heat to medium and cook for 10 minutes, stirring occasionally.

Pour in 4 cups of chicken or vegetable stock along with 1 teaspoon of ground cinnamon, ½ teaspoon of ground allspice, and a pinch of cayenne pepper. Bring to a boil, reduce heat to low, and simmer for 20 minutes.

Remove from heat and let the soup cool slightly for about 5 minutes. Puree the soup in batches until smooth.

Return the pureed soup to the pot, stir in ½ cup of heavy cream, and season with kosher salt and freshly ground black pepper to taste.