• 2 Tbsp. plus 1/2 cup extra-virgin olive oil
• 1 large onion , chopped
• 2 large cloves garlic , chopped
• 7 large russet potatoes (4 pounds), peeled and cut into 1-inch cubes
• 10 cups chicken stock
• 1/2 cup chopped toasted walnuts
• 1/2 cup sage leaves
• 1/2 cup parsley leaves
• 1/4 cup grated Pecorino cheese
• 1 tsp. salt plus more salt to taste
• Freshly ground pepper

In a large saucepan or stockpot, heat 2 tablespoons olive oil over medium heat. Add onions and cook, stirring occasionally, until caramelized and golden brown, about 12 to 15 minutes. Add garlic and cook, stirring, 30 seconds. Add potatoes and stock, and bring to a boil. Reduce to a simmer; cover and cook 25 to 30 minutes until potatoes are very tender.

Meanwhile, in a food processor combine walnuts, sage, parsley, cheese, and 1 teaspoon salt to make pesto. Pulse until finely ground. With the processor on, slowly add 1/2 cup olive oil. Transfer to a bowl.

Puree soup in batches in a food processor or blender (or with a hand blender). Season to taste with salt and freshly ground pepper. Ladle into bowls and top each with 1 teaspoon of pesto.