Preheat the oven to 180C/350F.
Grease a 23cm Le Creuset rectangular casserole dish.
Add the sliced peaches, sugar, lemon, juice, cinnamon, vanilla, and corn starch to the dish and toss well to combine. Bake for 20 minutes.
Whilst the peaches are baking, make the crumble topping.
To a large bowl add the flour, caster, sugar, and baking powder and give it a good mix. Add the melted butter, vanilla, and cream (or milk) and mix to combine.
While the peaches come out the oven after the first bake, crumble the topping over the fruit evenly. Return the dish to the oven and bake for a further 30 -35 minutes. If necessary loosely cover the dish with a piece of tin foil to prevent over browning.
Serve with vanilla ice cream.