Pat the chicken breasts dry and season both sides with salt, black pepper, garlic powder, and onion powder.
Heat olive oil in a skillet over medium-high heat and sear the chicken for 3-4 minutes on each side until golden brown. Transfer to a slow cooker.
In the same skillet, sauté sun-dried tomatoes for a minute, then add heavy cream, Parmesan cheese, and Italian seasoning. Stir until well combined and heated through.
Pour the creamy sauce over the chicken in the slow cooker, cover, and cook on low for 4-6 hours or high for 2-3 hours.
Once cooked, check that the chicken is tender, shred with a fork, and sprinkle with fresh basil before serving.