While the spaghetti squash is roasting prepare your filling by combining 1.5 cups of sliced bell pepper (you can use any color you have on hand), half of a red onion halved again and sliced and 3 cloves of minced garlic in a bowl. Sprinkle with 1.5 tsp of cajun seasoning. Set aside.
Slice your chicken breasts into 1/2 inch strips and place in another bowl. Sprinkle with 1.5 tsp of cajun seasoning and mix to coat.
In a cast iron skillet or other heavy bottomed pan heat 1 tbsp olive oil and 1/2 tbsp but over high heat until melted.
Add half of the chicken in a single layer (do not stir) and brown over high heat for one minute. Flip to the other side and brown, undisturbed, for an additional 1 minute.
Using a slotted spoon, remove chicken to a clean plate. Repeat the process with the remaining chicken until all chicken has been browned.
Add remaining 1 tbsp of olive oil and 1/2 tbsp butter to the pan. When melted, add in the pepers, onion and garlic. Season with a pinch of salt and cook, undisturbed, over high heat for about 1 minute. You want to get the veggies as dark as possible.
Add chopped tomatoes and cook for another 30 seconds.
Remove all vegetables from the pan into a clean plate or bowl.
With the pan still over high heat, pour in 1 cup of chicken broth to deglaze and continue to cook on high for 3-4 minutes, scraping the bottom of pans to catch any delicious brown bits.
Reduce heat to medium low and whisk in 3/4th cup of heavy cream, stirring/whisking constantly.
Cook sauce over medium-low heat for 2-3 minutes until the sauce begins to thicken a little.
Add in 1/2 tsp of cayenne pepper (if desired) and 1/4th cup of shredded parmesan and stir to combine.
Taste the sauce at this point to see if it needs any additional salt, pepper or cayenne. The level of heat is completely up to your personal preference!
Add browned chicken (and all the juices) and cooked vegetables to the pan and cook over medium heat for a minute until the mixture is bubbly and hot. Remove from heat.