Step 1: Cook the Pasta
Bring a large pot of well-salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Reserve 1 cup of the starchy pasta water before draining. This is a chef’s secret for adjusting the sauce consistency later. Drain the pasta and set it aside.

Step 2: Sear the Chicken
While the pasta cooks, pat the chicken cubes dry with paper towels and season generously with salt and pepper. Heat the olive oil in a large, heavy-bottomed skillet (cast iron or stainless steel are ideal) over medium-high heat. Add the chicken in a single layer, ensuring not to overcrowd the pan. Cook for 5-7 minutes, turning occasionally, until the chicken is cooked through and has a beautiful golden-brown sear on all sides. Remove the chicken from the skillet and set it aside on a plate.

Step 3: Build the Sauce Base
Reduce the heat to medium. In the same skillet, melt the 2 tablespoons of butter. Add the minced garlic and sauté for about 30-60 seconds, until fragrant. Be careful not to burn it. Pour in the chicken broth to deglaze the pan, using a wooden spoon to scrape up all the delicious browned bits (the fond) from the bottom. Let it simmer for 1 minute.

Step 4: Create the Creamy Pesto Sauce
Pour the heavy cream into the skillet and bring to a gentle simmer. Let it cook for 2-3 minutes, allowing it to thicken slightly. Reduce the heat to low. Whisk in the ½ cup of pesto until it is fully incorporated into the cream. The sauce will now be a beautiful pale green.

Step 5: Incorporate Cheese and Finish the Sauce
Gradually sprinkle in the 1 cup of grated Parmesan cheese, whisking constantly until the cheese has melted and the sauce is smooth. Stir in the lemon zest, lemon juice, and optional red pepper flakes. Taste the sauce and adjust seasoning with salt and pepper as needed.

Step 6: Combine Everything in the Skillet
Add the cooked, drained pasta and the seared chicken back into the skillet with the creamy pesto sauce. Using tongs, toss everything together gently until the pasta and chicken are evenly and thoroughly coated in the sauce. If the sauce is too thick, add a splash of the reserved pasta water, a tablespoon at a time, until it reaches your desired consistency.

Step 7: Garnish and Serve Immediately
Remove the skillet from the heat. Garnish generously with fresh basil, a sprinkle of toasted pine nuts, and an extra dusting of Parmesan cheese. Serve directly from the skillet for a beautiful, family-style presentation.