Bring a medium sauce pot of generously salted water to a boil. Add the orecchiette and cook until just tender, 7 to 8 minutes. Drain, reserving 1 cup pasta cooking water.
While the orecchiette cooks, prepare and cook the vegetables.

• Peel and thinly slice the yellow onion.
• Finely chop, press, or grate enough garlic to measure 1 teaspoon.
• Trim the root ends from the Brussels sprouts; cut the sprouts in half.

In a large frying pan over medium-high heat, warm 1 tablespoon butter or 1 to 2 tablespoons oil until hot but not smoking. Add the onion, season with salt, and cook, stirring often, until soft and browned, 8 to 10 minutes, reducing the heat as needed to prevent scorching. Pour in ¼ cup wine or water and cook at a vigorous simmer, scraping up any browned bits from the bottom of the pan, until the liquid has reduced by about half, 1 to 3 minutes.

To the pan with the onion, stir in the garlic and as much Aleppo chile as you like and cook until fragrant, about 1 minute. Add the Brussels sprouts and ½ cup pasta cooking water and bring to a boil. Reduce to a simmer and cook, stirring occasionally, until the sprouts are tender, 5 to 7 minutes.
While the Brussels sprouts simmer, prepare the lemon.

• Zest the lemon and cut into wedges; set aside the wedges for garnish.

To the pan with the sprouts, stir in the orecchiette and heat until warmed through, 2 to 3 minutes. Stir in more pasta cooking water, if dry. Remove from the heat and stir in the lemon zest, walnuts, and Parmesan. Season to taste with salt and pepper.

Transfer the pasta to individual bowls. Garnish with the lemon wedges and serve.

Chef’s Tip To get dinner on the table even faster, in Step 2, start cooking the onion while you finish prepping the garlic and Brussels sprouts.