Instructions
Step 1
Make the pasta: In a stand mixer fitted with the paddle attachment, beat the flour, oil, eggs, salt, and 2 tablespoons of warm water together on low speed until a shaggy dough forms. (If the dough looks dry, add more water 1 tablespoon at a time.) Switch to the dough hook attachment and knead on medium speed until smooth and elastic, 5–7 minutes.
Step 2
Turn the dough out onto a clean work surface and form it into a disk, then wrap tightly in plastic wrap and set aside to rest for at least 1 hour (up to 8).
Step 3
Line a baking sheet with parchment. Quarter the dough and rewrap all but one portion. On a lightly floured work surface, use a floured rolling pin to roll the dough quarter into a 1/16-inch-thick rectangle. Trim the ragged edges.Using a sharp knife or pizza cutter, cut the dough lengthwise into ½-inch-wide strips, then cut the strips crosswise into squares. Spread the quadrucci on the baking sheet (it is okay if they overlap a little) and repeat the process with the remaining dough.
Step 4
Fill a large pot with the stock and bring to a boil. Meanwhile, to a large skillet, add the oil, onion, and salt and turn the heat to medium. Cook, stirring occasionally, until soft and lightly browned, 6–8 minutes. Add the spinach and cook, stirring occasionally, until wilted, 1–2 minutes more. Remove from the heat and stir in the lemon zest.
Step 5
To the boiling stock, add the quadrucci and cook, stirring occasionally, until they float to the surface and are al dente, 2–3 minutes. To serve, divide the spinach mixture among six bowls, then ladle with the broth and quadrucci.