Season the chicken breasts with salt and pepper.
In a large, oven safe skillet, heat the olive oil over medium-high heat.
Add the chicken breasts and cook for roughly 5 minutes on one side to brown it. Flip and brown the other side for an additional 3-4 minutes.
Remove the chicken breasts and place in the slow cooker.
In a medium bowl, add the cornstarch, slow whisk in the chicken broth to make a slurry. Pouring the liquid into the cornstarch helps keep the lumps to a minimum.
Stir in the garlic, Italian seasoning, red pepper flakes, heavy cream, and sun-dried tomatoes.
Pour this mixture over the chicken.
Cover and cook on high for 2 ½ - 3 hours or on low for 5-6 hours.
When ready, stir in the parmesan cheese.
Serve with rice, angel hair pasta, or a mixed green salad.
Garnish with sliced fresh basil or chopped fresh parsley.