Preheat oven to 180C or 160C fan-forced.
To make the filling, combine mixed berries, sugar and starch together.
To make your crumble, rub in melted butter with plain flour and brown sugar.
In another bowl, whisk together both flours, baking powder, baking soda and salt. Set them aside.
In your stand mixer, cream together butter and sugar until light and fluffy on high speed.
Add in vanilla extract
Drizzle in an egg. Mix well.
Next, stir in plain yogurt.
Lastly, fold in dry ingredients on low speed until just combined.
Transfer into a 7 inch square pan lined with parchment paper.
Add in your filling for the next layer.
Finally, scatter over the crumble mix into your pan.
Bake it in the oven for about 50 minutes.
Let it cool, cut and serve. You may reheat it in toaster to get the crispy crumble.