In a bowl, combine the bite-sized chicken pieces with Cajun seasoning, garlic powder, smoked paprika, salt, and black pepper. Toss well to evenly coat the chicken.

Heat olive oil in a large skillet over medium-high heat. Add the seasoned chicken pieces and cook for about 5-7 minutes, stirring occasionally, until the chicken is cooked through and lightly browned. Remove chicken from skillet and set aside.

In a large pot of salted boiling water, cook bowtie pasta according to package instructions until al dente. Add broccoli florets during the last 3-4 minutes of cooking. Reserve 1/2 cup pasta water, then drain the pasta and broccoli together.

In the same skillet used for the chicken, melt butter over medium heat. Add minced garlic and crushed red pepper flakes (if using), sautéing until fragrant, about 1 minute.

Stir in Dijon mustard, lemon zest, and lemon juice, stirring to combine.

Return the cooked chicken to the skillet, tossing to coat in the lemon butter sauce. Cook together for 2-3 minutes to meld the flavors.

Add the drained pasta and broccoli to the skillet with the chicken and sauce. Pour in reserved pasta water and sprinkle grated Parmesan cheese on top. Toss all ingredients gently until well combined and the cheese is melted, creating a creamy texture.

Stir in chopped parsley and chives. Adjust seasoning with salt and black pepper to taste. Serve immediately with extra Parmesan cheese on the side.