Season the chicken. Pat the chicken dry.
In a small bowl, combine salt, pepper, onion powder, garlic powder, and smoked paprika. Rub evenly over the chicken.
Sear for flavor (optional but recommended). Heat olive oil in a skillet over medium-high. Sear chicken 2–3 minutes per side until lightly golden.
You’re not cooking it through—just building flavor.
Layer the slow cooker. Add garlic, sun-dried tomatoes, chicken broth, Italian seasoning, and red pepper flakes to the slow cooker. Nestle the chicken into the mixture, turning to coat.
Slow cook. Cover and cook on Low for 3.5–4.5 hours or on High for 2–3 hours, until the chicken is just cooked through and tender.
Finish the sauce. Stir in heavy cream, Parmesan, and butter. Cover and cook on Low for 15–20 more minutes, just until the sauce is smooth and slightly thickened.
Shred or slice. Remove the chicken and slice, cube, or shred it.
Return it to the sauce and stir to coat. Taste and adjust salt and pepper.
Serve. Spoon the chicken and sauce over pasta, rice, or mashed potatoes. Top with chopped basil or parsley and a pinch of extra Parmesan.