Bring a medium sauce pot of generously salted water to a boil. Separate the pappardelle so the noodles don’t clump together during cooking. Add the pappardelle and cook, stirring occasionally, until just tender, 3 to 5 minutes. Drain the pappardelle, reserving ¼ cup [½ cup] pasta cooking water. Return the pappardelle to the pot.
While the water heats and the pappardelle cooks, prepare the remaining ingredients and cook the vegetables.

• Peel and finely chop the shallots.
• Zest and juice the lemon, keeping the zest and juice separate. [Zest and juice 1 lemon; save the remaining lemon.]
• Strip the parsley leaves from the stems; coarsely chop the leaves.
• Using the bottom of a bowl or cup, lightly crush the hazelnuts for garnish.

In a large frying pan over medium heat, warm 1 tablespoon [2 TBL] oil until hot but not smoking. Add the shallots and as many chile flakes as you like, season generously with salt, and cook, stirring occasionally, until the shallots start to soften, 2 to 3 minutes. Stir in the pappardelle, reserved pasta cooking water, lemon zest, and parsley and cook until the liquid has thickened slightly, 1 to 2 minutes. Stir in the spinach (in batches if needed), peas, 1 tablespoon [2 TBL] lemon juice, and 2 tablespoons [3 TBL] butter (from your pantry) or 1 tablespoon [2 TBL] oil and cook until the spinach is just wilted, 1 to 2 minutes.
Remove from the heat and season to taste with salt and pepper.

Transfer the pappardelle to individual bowls and crumble the ricotta salata over the top. Garnish with the hazelnuts and serve.