Lightly grease the inside of the crockpot with cooking spray or olive oil to help prevent sticking.
Place the chicken breasts in the bottom of the slow cooker in a single layer for even cooking.
Sprinkle the diced onion, minced garlic, salt, black pepper, Italian seasoning, and paprika evenly over the chicken.
Add the butter on top and drizzle the olive oil across the ingredients.
Slowly pour the chicken broth into the crockpot around the chicken.
Cover with the lid and cook on low for 5 to 6 hours or high for 3 to 4 hours until the chicken is tender and fully cooked.
Remove the cooked chicken from the crockpot and place it onto a plate or cutting board.
Shred the chicken into small pieces using two forks, then return the shredded chicken back into the crockpot.
Stir the uncooked orzo pasta into the broth and chicken mixture until evenly combined.
Cover again and cook on high for 20 to 30 minutes, stirring once or twice during cooking, until the orzo becomes soft and tender.
Pour in the heavy cream and stir slowly until fully mixed into the pasta.
Add the grated parmesan cheese a little at a time while stirring so it melts smoothly into the creamy sauce.
Stir the fresh spinach into the hot pasta mixture and continue stirring until the spinach wilts completely.
Let the chicken orzo sit uncovered for about 5 minutes before serving so the sauce thickens slightly.
Serve warm with extra parmesan cheese and black pepper if desired.