Penne with Melted-Vegetable Sauce

Ingredients

• Kosher salt
• 1 large russet potato, peeled and cut into 1/4-inch dice
• 2 medium carrots, peeled and cut into 1/4-inch dice
• 3 ounces string beans, trimmed and cut into 1/4-inch dice
• 1/2 small fennel bulb, trimmed and cut into 1/4-inch dice
• 1 small red onion, cut into 1.4-inch dice
• 1 pound dried penne
• 2 to 4 medium cloves garlic, minced
• 3/4 cup extra-virgin olive oil
• 1/4 cup minced parsley
• Freshly ground black pepper
• Grated Parmigiano-Reggiano, for serving

Directions

1. Bring a medium pot of salted water to a boil. Add the potato and cook until you can press a piece apart easily with your fingers, about 5 minutes. Lift it out with a fine strainer and move it to a large mixing bowl. Cook the carrots, string beans, fennel, and onion separately in the same water, one after another, until each is very tender, about 5 minutes each; as each vegetable finishes, add it to the bowl.
2. Add the penne to the boiling water and cook it to al dente according to the package directions. Drain the pasta, saving 1 cup of the pasta water.
3. While the pasta cooks, put the garlic, olive oil, and parsley into the bowl with the vegetables. Stir everything well, letting the potatoes collapse into a chunky puree. Season with salt and pepper.
4. Add the penne and a generous grating of Parmigiano-Reggiano to the vegetable sauce, then toss until combined. If the sauce feels too thick, loosen it with the reserved cooking water, 1 tablespoon at a time. Spoon into bowls, finish with more grated cheese, and serve.