Step 1: Season the Chicken - Place the chicken breasts in a 6 or 7 quart slow cooker, then season them with the kosher salt, black pepper, and garlic powder. I like getting those seasonings directly onto the chicken rather than simply dropping everything into the broth. It means the meat itself has good flavor once you shred it later, which matters when you are trying to get a little chicken into every spoonful.
Step 2: Add the Onion and Garlic - Scatter the diced onion and minced garlic around and over the chicken. There is no need to cook them first. During the long cooking time, the onion will soften and mellow while the garlic works its way into the broth. This is one of those moments when I appreciate the slow cooker most because there is no extra skillet waiting in the sink afterward.
Step 3: Build the Savory Broth - Pour in the chicken broth. Add the cream of chicken soup and whisk or stir it into the broth as thoroughly as you can until the larger lumps disappear. Add the chicken bouillon, Italian seasoning, paprika, and crushed red pepper flakes. Give the liquid another gentle stir around the chicken so the seasonings are distributed throughout the cooker.
Step 4: Add the Sun Dried Tomatoes - Stir in the drained sun dried tomatoes. They will soften as the soup cooks and give the broth little pockets of concentrated tomato flavor. Make sure they are mostly tucked into the liquid rather than sitting on top. Then cover the slow cooker so all that garlic, chicken, herb, and tomato aroma stays where it belongs.
Step 5: Slow Cook Until Tender - Cook on LOW for 6 to 7 hours or on HIGH for 3 to 4 hours. The chicken should be fully cooked and tender enough to pull apart easily. I prefer the LOW setting when the day allows for it because it gives the chicken plenty of time to become tender while dinner quietly takes care of itself.
Step 6: Shred the Chicken - Transfer the cooked chicken to a plate or cutting board. Shred it with two forks or chop it into bite sized pieces if your family prefers chunkier chicken. I usually shred ours because the smaller strands settle right into the creamy broth and make it easier for everybody to get chicken, pasta, and sauce together in one spoonful.
Step 7: Cook the Ditalini - While the chicken is out of the slow cooker, cook the ditalini pasta according to the package directions until just al dente. Drain it well once it is ready. Cooking the pasta separately is worth the extra pot because it gives you much better control over the texture and keeps those little noodles from sitting in hot broth for hours and turning too soft.
Step 8: Make the Soup Creamy - Return the shredded chicken to the slow cooker. Add the softened cream cheese, heavy cream, grated Parmesan, and cooked ditalini. Stir gently until the cream cheese begins melting into the hot broth and the Parmesan disappears into the soup. Give it a minute if needed. The broth will go from savory and brothy to noticeably richer and silkier as everything comes together.
Step 9: Wilt the Spinach - Add the chopped fresh spinach and stir it into the hot soup. Let everything cook for another 3 to 5 minutes, just until the spinach wilts and the creamy ingredients are completely incorporated. You are not trying to cook the spinach for a long time here. You want it tender and bright, not cooked down until it disappears.
Step 10: Finish With Fresh Parsley - Ladle the soup into bowls and sprinkle the chopped parsley over the top. Give the broth a taste before serving and adjust the seasoning if needed. Then put the pot somewhere everybody can reach it, set out some bread for dipping, and prepare yourself for somebody to ask whether there is enough for another bowl.