Creamy Chicken and Flat Dumplings

Ingredients

• 1 medium onion
• 2 TBSP unsalted butter, cut into pieces
• 3 medium carrots
• 8 cups water
• large pinch salt
• 2 cups all-purpose flour
• ¾ tsp baking powder
• ¾ cup milk
• 2 tsp kosher salt
• 2 cloves garlic, peeled and smashed
• 1 whole fryer chicken (about 4 pounds)
• 3 stalks celery