Season and sear the chicken: Toss the chicken with 2 tablespoons of the cajun seasoning until evenly coated. Heat the olive oil in a large skillet over medium-high heat and sear the chicken for 6-7 minutes, stirring occasionally, until browned with charred edges and no longer pink in the center. Transfer to a plate.

Cook the pasta: While the chicken cooks, boil the penne in salted water according to the package directions until al dente. Drain and set aside.

Sauté the vegetables: Melt the butter in the same skillet. Add the bell peppers and onion and cook for 4-5 minutes until just softened. Stir in the garlic and cook for 30 seconds.

Build the sauce: Stir in the chicken broth, scraping up any browned bits from the bottom of the pan. Add the cream cheese in cubes and stir until melted and smooth.

Add the cream and parmesan: Reduce the heat to low and stir in the heavy cream, parmesan, remaining 1 tablespoon cajun seasoning, smoked paprika, and salt until the sauce is smooth.

Combine and finish: Return the chicken and any juices to the skillet along with the cooked pasta. Toss to coat and simmer for 2-3 minutes until the chicken is heated through and reaches 165°F.

Garnish and serve: Sprinkle with sliced green onions and serve warm.