Optional step, season chicken on both sides with seasoning salt or salt and black pepper and sear in a large skillet on high heat, 1-2 minutes per side.
Pour the oil from the sun-dried tomatoes jar into a large crockpot. Place the tomatoes on a cutting board, and roughly chop them into bite-sized pieces.
Add the chopped tomatoes to the crockpot along with chicken broth, garlic powder, Italian seasoning, crushed red pepper flakes (if using), and seasoning salt or salt and black pepper. Stir until well combined.
Add the seared or non-seared chicken to the crockpot. Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chicken is cooked through and tender.
About 30 minutes before serving, carefully remove the chicken from the crockpot and to plate. Using two forks, pull the chicken apart into large pieces.
In a bowl, mix together the heavy cream, cornstarch, and grated parmesan. Pour the cream mixture into the crockpot, stirring to combine with the sauce.
Return the chicken to the crockpot, cover, and allow it to heat through for about 30 minutes on high heat. Taste and adjust the seasonings as desired.
Once ready, serve the creamy chicken over pasta, rice, or mashed potatoes. Garnish with fresh basil if desired.