Select saute setting on a 6-qt. electric pressure cooker and adjust for medium heat; add 1 tablespoon oil. When oil is hot, cook and stir peppers until crisp-tender, 3-4 minutes. Remove and keep warm. Heat remaining 1 tablespoon oil. Add chicken and 1 tablespoon Cajun seasoning. Cook and stir until browned, 3-4 minutes. Press cancel.
Add pasta, stock and water (do not stir). Lock lid; close pressure-release valve. Adjust to pressure cook on high for 6 minutes. Let pressure release naturally for 3 minutes; quick-release any remaining pressure. Press cancel.
Select saute setting, and adjust for low heat. Stir in cream, Parmesan cheese, remaining 1 tablespoon Cajun seasoning and reserved peppers. Cook until heated through (do not boil).