Remove the stems from the mustard greens and chop the leaves (you should have about 2 cups, reserve any extra for another use). Chop the baby broccoli florets and toss the stems. Chop 4 cloves of garlic. Rinse and drain the cannellini beans.

Bring a large pot of salted water to a boil. Add 1 cup of the pasta and cook until al dente, 8 minutes or according to package instructions. Drain the pasta, drizzle with 1 tablespoon olive oil, and toss to separate the pieces.

Return the pot to medium-high heat, and warm 2 tablespoons olive oil. Add the mirepoix, season with salt, and sauté until soft, 5 minutes. Add the garlic and a pinch of chile flakes, if you want a kick, and stir until fragrant, 30 seconds.

Add the cannellini beans and vegetable broth, bring to a simmer, and cook to let the flavors meld, 10 minutes.

Add the chopped baby broccoli, mustard greens, and cooked pasta, and cook until the pasta is warmed through and the mustard greens are wilted, 3 minutes. Remove from the heat, add the juice of 1 lemon, and season with salt and pepper, if necessary.

Ladle the soup into bowls and swirl with spoonfuls of the pistachio pesto. Sprinkle with Parmesan, grind with pepper, and serve warm.