First, melt the butter and sun-dried tomato oil in a saucepan over medium heat. Add the minced garlic and sauté for just about 20 seconds – don't let it brown!
Next, pour in the chicken stock and heavy cream, bringing it to a gentle simmer for about 8 minutes, or until the sauce begins to thicken nicely.
Finally, stir in the Parmesan cheese and let it simmer for another 3-5 minutes until it's perfectly creamy.
Place your boneless, skinless chicken thighs directly into your slow cooker insert. Season them generously with the dried basil, oregano, parsley, salt, and pepper.
Arrange the sliced sun-dried tomatoes over the seasoned chicken. Carefully pour the creamy sauce you just made all over everything.
Cook on high for 3 hours, or on low for 6 hours, until the chicken is wonderfully tender.
Once cooked, gently remove the chicken and set it aside. Stir the fresh baby spinach into the hot sauce in the slow cooker, then cover and let it sit for a few minutes until the spinach is perfectly wilted.
Serve your delicious Tuscan chicken with plenty of the flavorful sauce drizzled over top.