Melt butter and olive oil in a large pot over medium heat
Add diced onion and cook for 4–5 minutes until soft
Stir in garlic and cook for 30 seconds until fragrant
Sprinkle flour over the onions and stir for 1–2 minutes
Slowly whisk in chicken broth until smooth
Add cooked chicken, milk, and heavy cream
Season with salt and black pepper
Bring to a gentle simmer and cook for 10 minutes
In a bowl, mix dumpling flour, baking powder, and salt
Stir in milk and melted butter until a soft dough forms
Drop spoonfuls of dough into the simmering broth
Cover the pot and reduce heat to low
Cook for 12–15 minutes without lifting the lid
Gently stir once dumplings are cooked through
Taste and adjust seasoning if needed
Garnish lightly if desired and serve hot