On the Instant Pot set it to the saute function.

Pat the chicken breast dry with a paper towel and sprinkle both sides of the chicken with the Cajun seasoning.

Add the olive oil to the Instant Pot.

When the oil is hot add the chicken and brown both sides of the chicken, about 3-4 minutes per side. The chicken will not be fully cooked but this is ok.

Remove the chicken breasts and add them to a plate.

To the Instant Pot add the garlic and cook for 30 seconds or just until fragrant.

Pour in the chicken stock and scrape the bottom of the pan to pick up any brown bits stuck on the pan from browning the chicken.

Add the heavy cream, pasta, and kosher salt.

Do your best to push the pasta under the surface of the liquid but resist stirring too much.

Add the chicken back to the top of the pasta mixture.

Attach the lid and ensure the valve is in the "sealing" position.

Turn the Instant Pot to "manual" and set it for 4 minutes.

Once the Instant Pot has finished cooking release the pressure manually by switching the valve to the "venting" position. BE CAREFUL HOT STEAM WILL COME OUT OF THE VALVE.

When fully depressurized the lid will unlock and you can remove the lid.

Remove the chicken from the Instant Pot and slice or shred the chicken.

Add the thyme, Parmesan cheese, and butter to the pasta and stir until they have melted.

Serve the pasta topped with chicken, diced tomatoes, and parsley.