Bring a large pot of salted water to a boil. Cook the linguine according to the package directions until al dente.

Before draining, reserve about 1 cup of pasta cooking water. Drain the linguine and set aside.

While the pasta cooks, place the bite-size chicken pieces in a bowl. Add the cornstarch, ½ teaspoon salt, ½ teaspoon black pepper, and garlic powder.

Toss until every piece of chicken is evenly coated.

Heat the oil in a large skillet over medium heat.

Add the chicken once the oil is hot. Cook for 6–7 minutes, turning occasionally, until golden on the outside and completely cooked through. The thickest pieces should reach 165°F (74°C).

Transfer the cooked chicken to a clean bowl or plate and keep warm.

Check the skillet. There should be a small amount of oil remaining; add another splash if the pan looks dry.

Add the finely chopped onion and cook for 2–3 minutes, stirring frequently, until it begins to soften.

Add the minced garlic, ¼ teaspoon salt, and ½ teaspoon black pepper. Cook for about 1 minute, stirring so the garlic doesn't burn.

Pour in the chicken stock and heavy cream. Stir well, scraping up any flavorful browned bits from the bottom of the skillet.

Bring the mixture to a gentle simmer and cook for approximately 3 minutes, until it begins to thicken.

Stir in the fresh lemon juice.

Add the drained linguine to the skillet and sprinkle the finely grated Parmesan over the pasta.

Using tongs, gently toss the Garlic Parmesan Chicken Pasta until the cheese melts and the linguine is thoroughly coated in the creamy sauce.

If the sauce is thicker than desired, add the reserved pasta water a small splash at a time, tossing between additions until it reaches a smooth, glossy consistency.

Return the cooked chicken to the skillet. Toss everything together and cook for another minute until the chicken is hot.

Divide between serving bowls and finish with chopped parsley, freshly ground black pepper, and additional grated Parmesan.