Add Cajun seasoning, garlic powder, onion powder, cayenne, salt, and black pepper to a small dish and whisk to combine. Separate half of the spice mixture into a separate bowl, and set aside.

In a large frying pan or braiser (a lid is required), heat 1 tbsp of oil over medium heat. Add garlic sausage and fry both sides until golden brown, about 2 minutes per side. Remove sausage from pan and place onto a paper-towel lined plate.

Add another 1 tbsp of oil to the pan, then add chicken. Season with half of the seasoning mixture. Fry the chicken pieces until cooked through, about 5 minutes, and then place onto plate with sausage.

Turn pan to medium-low heat, and add last 1 tbsp of oil to pan. Add peppers and onion, and sprinkle with some salt. Use the onion to deglaze the pan, scraping at any brown bits (fonon the pan. Fry vegetables until about halfway cooked, about 5-6 minutes.

Add remaining spices and 2 tbsp of flour to the vegetables. Mix to combine, and cook for 1 minute. Add chicken broth, whole milk, and penne to pan, mix to combine. Cover the pan and simmer for about 22 minutes, ensuring that you stir every few minutes to ensure no sticking.

When the pasta is cooked through, add the heavy cream, and mix to combine. Then add the 2 tbsp of cold butter, and mix it in by continuously stirring until the butter is well emulsified. Finish with the lemon juice and add back in the chicken and sausage, then mix everything well to combine. Season with salt and pepper if needed.