Pre-heat the oven to 180C.

Chop the chicken breasts into bite-sized chunks. Wash the broccoli and break into small florets.

Sautée the onion in the olive oil until translucent. Add the chicken pieces and sautée on high heat until just cooked (if using raw chicken) or just heated . Add the broccoli in the last few minutes, mixing well, and season to taste. Spoon the broccoli chicken mixture into a warmed ovenproof dish and keep warm.

Deglaze the pan with a splash of white wine, then lower the heat to medium and add the chicken stock. Bring to the boil. In the meanwhile, mix the softened butter and flour into a paste. Add this a teaspoonful at a time to the stock, stirring to eliminate lumps – the sauce should gradually thicken as each teaspoon is added. When the sauce has reached the desired consistency, stir in the mustard and pour the sauce over the chicken broccoli mix.

Sprinkle half the breadcrumbs over the dish, then the cheese, followed by the rest of the breadcrumbs to form a crust. Bake uncovered at 180C for about 20 minutes or until the cheese has melted and the bake is bubbling. Finish under a grill to crisp and serve on brown rice.