Bring a large pot of salted water to a boil. Add bowtie pasta and cook according to package directions until al dente. In the last 3 minutes of cooking, add broccoli florets. Reserve 1/2 cup of pasta water before draining. Drain and set aside.

Season chicken pieces with Cajun seasoning, garlic powder, smoked paprika, salt, and pepper. Toss until evenly coated.

Heat olive oil in a large skillet over medium-high heat. Add chicken in a single layer and sear undisturbed for 2 to 3 minutes. Turn and cook until golden brown and fully cooked through, about 6 to 7 minutes total. Confirm internal temperature reaches 165 degrees F. Remove and set aside.

Lower heat to medium. Add butter to the same skillet and melt, scraping up the browned bits. Add minced garlic and cook for 1 minute until fragrant. Do not let it burn.

Stir in red pepper flakes, Dijon mustard, lemon juice, and lemon zest. Add parsley and chives. Season with salt and pepper.

Return chicken, pasta, and broccoli to the skillet. Toss to coat in the sauce. Add reserved pasta water a small splash at a time until the sauce is smooth and silky.

Stir in Parmesan cheese until melted and creamy. Serve warm with extra Parmesan and fresh herbs on top.