Step 1: Season the Chicken - Start by laying your chicken breasts out on a plate or cutting board, then sprinkle them with the salt, pepper, and garlic powder. I like to season both sides because chicken breasts need a little help in the flavor department, especially when they are going to cook slowly in sauce. This first layer of seasoning makes the whole dish taste more homemade instead of just creamy.
Step 2: Sear the Chicken - Warm the oil in a skillet over medium high heat, then add the seasoned chicken breasts. Let them cook for about 2 to 3 minutes on each side, just until they get lightly browned. You are not trying to cook them through here. You are just giving them a little color and flavor before they settle into the slow cooker. That small step makes a big difference, and it gives the finished chicken a more restaurant style taste.
Step 3: Add the Chicken to the Slow Cooker - Place the browned chicken breasts into the bottom of your slow cooker in an even layer. Try not to stack them if you can help it. When the chicken sits evenly, it cooks more consistently and gets coated in that creamy cheddar sauce all the way around. At this point, it already looks like dinner is headed in the right direction.
Step 4: Add the Broccoli - Scatter the broccoli florets around and over the chicken. If your family likes softer broccoli, add it now and let it cook the whole time. If you like broccoli a little firmer and brighter, you can hold it back and add it during the last 1 to 2 hours. Around my house, I usually add it at the beginning because I like how it melts into the sauce and makes the whole dish feel like a true casserole.
Step 5: Mix the Cheddar Sauce - In a large bowl, whisk together the cream of chicken soup, sour cream, chicken broth, 1 and 1 half cups of shredded sharp cheddar cheese, onion powder, and paprika. Stir until everything looks smooth and creamy. The sauce may look a little thick, but that is just fine. As it warms up in the slow cooker, the cheese melts, the broth loosens things up, and the chicken releases a little juice of its own.
Step 6: Pour the Sauce Over Everything - Pour the cheddar sauce evenly over the chicken and broccoli. Use a spoon to spread it around so everything gets covered. This is where the recipe starts looking like that cozy broccoli cheddar chicken dinner you had in mind. Make sure the chicken is mostly covered so it stays tender while it cooks.
Step 7: Cook Until Tender - Cover the slow cooker and cook on low for 5 to 6 hours or on high for 3 to 4 hours. The chicken should be tender and cooked through, and the sauce should be hot and creamy. If you have a meat thermometer, the chicken is done when it reaches 165 degrees Fahrenheit in the thickest part. I like cooking this on low when I can because the chicken stays especially tender.
Step 8: Make the Buttery Cracker Topping - When the chicken is cooked, stir the crushed buttery crackers and melted butter together in a small bowl. You want the crumbs evenly coated so every spoonful has that rich, buttery flavor. This topping is what gives the dish its casserole personality, and honestly, it is the part everyone seems to notice first.
Step 9: Add Cheese and Cracker Crumbs - Sprinkle the remaining 1 half cup of cheddar cheese over the chicken mixture, then scatter the buttery cracker crumbs on top. Cover the slow cooker again for 10 to 15 minutes, just until the cheese softens and melts a bit and the topping warms through. The crackers will soften slightly in the slow cooker, which gives the dish that cozy homestyle texture.
Step 10: Broil for a Crispier Finish - For a more baked casserole texture, carefully transfer the chicken and sauce to a baking dish, add the cheese and cracker topping, then broil for 2 to 3 minutes. Keep an eye on it because cracker crumbs can go from golden to too dark pretty quickly. This step is optional, but it does give the topping a little extra crunch.
Step 11: Finish with Parsley and Serve - Sprinkle chopped parsley over the top right before serving. It adds a fresh color and makes the whole dish look like you fussed over it more than you did. Spoon the chicken, broccoli, sauce, and topping onto plates and make sure everyone gets some of those buttery crumbs.