Bring a large pot of salted water to a boil and cook the pasta until al dente according to package directions; drain and set aside.
In a shallow bowl combine the Panko and 1/2 cup of the grated Parmesan. Pat the chicken dry and dredge both sides in the Panko mixture, pressing the crumbs to adhere.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the Panko-coated chicken and cook 3–4 minutes per side, until golden and cooked through; transfer to a cutting board, season with salt, and slice into thin strips.
In the same skillet, add the remaining 2 tablespoons olive oil and heat over medium-high. Sauté the chopped onion 4–5 minutes until softened, then add the chopped bell peppers and garlic and cook another 4–5 minutes until the peppers are tender.
Stir in the Cajun seasoning, a pinch of crushed red pepper flakes, and salt and black pepper to taste; cook 1 minute until fragrant.
Pour in the milk and heavy cream (or coconut milk) and add the cream cheese. Whisk until smooth, bring to a gentle simmer, and cook 5–8 minutes until the sauce thickens slightly.
Stir in the remaining 1 cup (about) grated Parmesan until melted and smooth. Add the drained pasta to the sauce, toss to combine, and cook 3–5 minutes to heat through.
Remove from the heat, stir in the chopped parsley, divide the pasta among plates, and top with sliced Panko-crusted chicken.
