Sear the Chicken: Set the Instant Pot to SAUTE mode. Heat the sun-dried tomato oil and melt the butter. Season the chicken with salt and pepper. Sear the chicken for 2-3 minutes on each side until golden brown. Remove the chicken and set it aside.
Cook Garlic: Add minced garlic to the pot and cook for 30 seconds or until fragrant.
Deglaze the Pot: Pour in the chicken stock to deglaze the pot, scraping up any bits stuck to the bottom. These bits contain flavor that will enrich your sauce.
Season: Stir in Italian seasoning, salt, pepper, and chili flakes (optional).
Pressure Cook: Return the chicken to the pot. Secure the Instant Pot lid, set the vent to SEALING, and select the PRESSURE COOK setting for 5 minutes (8 minutes for bone-in chicken thighs). Once the cooking time ends, release the steam manually.
Make the Creamy Sauce: Remove the chicken, set it aside, and switch the Instant Pot to SAUTE. Stir in the heavy cream and freshly grated parmesan cheese until smooth and creamy.
Add Vegetables: Add the chopped sundried tomatoes and spinach leaves. Stir until the spinach wilts and is well incorporated into the sauce.
Serve: Return the chicken to the pot, spoon the creamy sauce over it, and serve over pasta or rice with extra grated parmesan if desired.