01 - Arrange the chicken breasts in an even layer at the bottom of the slow cooker insert.
02 - Scatter the chopped onions, minced garlic, and broccoli florets evenly over the chicken.
03 - In a medium mixing bowl, whisk together the chicken broth, softened cream cheese, sour cream, milk, Dijon mustard, paprika, salt, and black pepper until completely smooth and well combined.
04 - Pour the prepared sauce mixture evenly over the chicken and vegetables, ensuring all ingredients are coated.
05 - Cover and cook on HIGH setting for 4 hours or LOW setting for 6 to 7 hours, until the chicken is tender and reaches an internal temperature of 165°F.
06 - About 30 minutes before serving, shred or slice the chicken directly in the slow cooker using two forks. Stir in the shredded sharp cheddar cheese until melted and thoroughly incorporated.
07 - For a thicker consistency, whisk the cornstarch with 2 tablespoons of cold water to create a slurry. Stir into the slow cooker and cook for an additional 15 to 20 minutes until the sauce thickens.
08 - Taste the dish and adjust salt or pepper as needed. Serve hot, garnished with additional cheddar cheese or fresh herbs if desired.