Prepare the broccoli and scallions before handling the raw chicken. Cut the chicken on a separate board, then wash hands and clean the utensils and work surface. Keep cooked food away from the raw chicken plate.

Bring a large pot of water to a boil and salt it as desired. Add the penne and cook according to the package directions. Add the small broccoli florets during the last 2–3 minutes, checking that both pasta and broccoli reach your preferred texture. Reserve 1/2 cup cooking water, then drain.

Meanwhile, whisk mayonnaise, sweet chili sauce, lime juice and 1 teaspoon sriracha in a small bowl. Set the sauce aside, away from the raw chicken preparation area.

Toss the chicken with garlic powder, smoked paprika, fine salt and black pepper. Heat the olive oil in a large skillet over medium-high heat. Add the chicken in a single layer, working in batches if necessary.

Cook the chicken, turning as needed, until browned and a food thermometer inserted into the thickest pieces reads 165°F (74°C). Begin checking after approximately 6 minutes; the total time depends on piece size, pan and heat. Use a clean plate if transferring a cooked batch out of the skillet.

Take the skillet off the heat and let it stand for about 2 minutes. Return any cooked chicken to the skillet, then add the drained penne and broccoli. Fold in the sauce. Add reserved pasta water one tablespoon at a time, only until the sauce coats the ingredients easily. Do not bring the mayonnaise sauce to a boil.

Taste and adjust with a little extra sriracha if wanted. Scatter the sliced scallions over the pasta and serve promptly.