Cook the penne pasta in a large pot of salted boiling water until al dente. Right before draining, reserve ¼ cup of the starchy pasta water, then drain the pasta and set aside.

Season both sides of the chicken cutlets evenly with Italian seasoning, garlic powder, smoked paprika, salt, and pepper. Heat 1.5 tbsp olive oil in a large skillet over medium-high heat. Sear the chicken for 5–6 minutes per side until a golden-charred crust forms and the internal temperature hits 165°F. Remove from the pan, let rest for 5 minutes, then slice.

Lower the skillet heat to medium. Add 2 tbsp olive oil, minced garlic, and sliced sun-dried tomatoes to the remaining pan juices; sauté for 1 minute until highly fragrant. Pour in the chicken broth and lemon juice, using a wooden spoon to scrape up all the browned bits from the bottom of the skillet. Simmer for 2 minutes to reduce slightly.

Add the fresh baby spinach to the skillet, stirring continuously for 1–2 minutes until it just wilts down into the liquid.

Return the cooked penne and sliced chicken back into the skillet. Toss everything together well to coat the pasta in the glossy sauce, adding the reserved pasta water a tablespoon at a time if needed to loosen. Turn off the heat completely and gently fold in the crumbled feta cheese so it stays in soft crumbles. Plate hot and garnish with red chili flakes and fresh herbs if desired.