Crock-Pot Cheesy Chicken Broccoli Soup

Ingredients

• 1 lbboneless skinless chicken breasts
• 5 c.chicken broth
• 0.75 lb.peeled baby potatoes, cut into1/4" cubes
• 1 largehead of broccoli, cut into small florets
• 1 onion, chopped
• 1 koshersalt
• 1 Freshlyground black pepper
• 0.25 c.flour
• 1 c.heavy cream
• 1.5 c.shredded Cheddar, plus more for garnish
• 0.5 c.grated Parmesan
• 1 Sourcream, for serving