Bring a large pot of salted water to a boil. Cook the bowtie pasta according to package directions until al dente. Add broccoli florets during the last 3 minutes of cooking. Reserve 1/2 cup of the pasta water, then drain and set aside.

In a bowl, season the chicken pieces with Cajun seasoning, garlic powder, smoked paprika, salt, and pepper.

Heat olive oil in a heavy-bottomed cast iron skillet over medium-high heat. Cook the seasoned chicken until golden and cooked through, about 6–7 minutes. Remove the chicken and set it aside.

Lower the heat to medium and add the butter to the skillet. Once melted, add the minced garlic, cooking until fragrant. Stir in crushed red pepper flakes (if using), Dijon mustard, lemon juice, and lemon zest. Season with salt and pepper to taste.

Return the cooked chicken, pasta, and broccoli to the skillet. Toss gently to coat everything in the buttery sauce. Add reserved pasta water as needed to achieve desired creaminess.

Stir in the grated Parmesan cheese until melted and creamy.

Transfer to plates, garnishing with extra Parmesan and fresh herbs.