In a mixing bowl, combine garlic powder, onion powder, chili powder, paprika, salt, and pepper.
Add chicken and toss with your hands to coat the chicken with spices.
Select Sauté and preheat the pressure cooking pot.
When hot, add the butter and oil and stir until butter is melted.
Briefly sauté the chicken a few pieces at a time on both sides and remove to a plate.
When all the chicken has been sautéed, add the chicken broth and chicken to the pressure cooking pot.
Lock the lid in place. Select high pressure and 3 minute cook time.
When time beeps, do a quick pressure release to release the pressure.
In a small bowl, dissolve cornstarch in water.
Push chicken to one side of the pot and add cornstarch mixture and stir to combine.
Select Sauté and constantly stir until sauce thickens.
Turn off pressure cooker and gradually stir in heavy cream.
Serve chicken and sauce over spaghetti sprinkled with parsley.