Preheat the oven to 450°F (230°C). Use an oven-safe 9-inch pie plate suitable for this temperature.

Put the chopped broccoli into a saucepan and add enough water to cover it. Bring to a boil and cook for about 5 minutes, until tender. Drain well.

Arrange the drained broccoli across the pie plate. Distribute the cubed cooked chicken over it.

In a separate bowl, stir the condensed cream of broccoli soup and milk together. Pour the mixture over the chicken.

Scatter the Cheddar over the sauce.

Stir the bread crumbs into the melted butter in a small bowl. Sprinkle the buttered crumbs over the cheese.

Bake uncovered for about 15 minutes, until bubbling and golden on top. Check that the center is heated through to 165°F (74°C); continue baking if needed. Serve hot.