Preheat oven to 175°C (350°F).
Grease a low sided casserole dish with butter (around 20-22 cm)
Add all the filling ingredients into a bowl and mix until combined well. Pour into your prepared dish.
Bake Casserole for 30 minutes.
While the casserole is cooking combine all the topping ingredients in a bowl and mix well.
Remove the casserole from the oven after 30 minutes and top with the mixed topping ingredients, make sure its nice and thick but depending on the size of your pan you may have some left over.
Return to the oven and bake for a further 15 minutes or until your topping is nice and brown.