For the soup: In a small food processor, puree 1/4 cup of the butter beans until smooth. Set aside.
Place a heavy saucepan or stockpot over medium-low heat and add the olive oil. Add the leeks and garlic and sweat until translucent and softened, about 6 minutes. Season with salt and pepper. Add the stock, pasta, pearl onions, tomatoes and remaining butter beans. Bring to a simmer and simmer until the pasta is cooked, about 5 minutes. Check the seasoning. Add the haricot vert and cook for another 3 minutes. Stir in the bean puree, spinach, peas and parsley.
For serving: Transfer to serving bowls and garnish with a small spoonful of pesto, some radishes, cilantro and scallions, a drizzle of olive oil and a sprinkle of Parmesan.