Umbrian Vegetable Soup (Zuppa di Verdure all’Agliata)

Ingredients

• 1⁄2 cup packed basil leaves
• 1⁄4 cup extra-virgin olive oil, plus more for drizzling
• 2 tbsp. minced fresh flat-leaf parsley
• 4 cloves garlic
• 1⁄2 medium onion, cut into chunks
• 8 oz. red new potatoes, cut into 1⁄2" cubes
• 3 stalks celery, minced
• 2 medium carrots, minced
• 2 plum tomatoes, cored and minced
• Kosher salt, to taste
• 3 oz. spinach, trimmed and rinsed (about 2 loosely packed cups)
• 1 1⁄2 cups canned cannellini beans, rinsed
• 1 cup fresh or frozen green peas
• 1⁄2 small head frisee, leaves cut into bite-size pieces (about 2 cups)
• Freshly ground black pepper, to taste
• Freshly grated Grana Padano or parmesan, for serving