Melt butter in large dutch oven or oven-proof pot over high heat. Saute onion 2 min. Add chicken and garlic, sprinkle across garlic powder, salt and pepper. Cook until surface of chicken is sealed.
Stir in flour, then chicken stock – stir until it goes milky coloured (indicates flour is dissolved). Stir in milk, salt, pepper and macaroni. Scatter broccoli across surface, bring to simmer, put lid on and transfer to oven preheated to 180C/350F (160C fan-forced).
Bake 20 min, remove lid, flick to oven grill/broiler on high. Stir in cheese (will seem watery still, that’s what we want), smooth surface, sprinkle with crunchy topping, put under grill for 3 min or until topping is golden. Serve – and marvel at creamy cheesy sauce!
