Apple Crumble dilemma? Cook the apples first?

To get a really crunchy crumble topping you can put the crumble mixture (it's also good to add breadcrumbs and/or oats) into a large frying pan and begin to brown, turning continuously with a spatula.
I saw this demonstrated by Raymond Blanc and it's the method I saw being used in the working kitchen of a National Trust property over an open fire (possibly Waddesdon Manor). Works every time. You can even make the filling and crumble separately on the stove top and assemble in individual ramekin dishes.

I make a large batch of crumble mixture, cook it turning it over seversal imes as it cooks, when cool I put it through the liquidiser to break up any lumps and then freeze it for future use. Then for whatever crumble you want, book your fruit and then put the ready cooked crumble on top. So you can preapre ahead of time then just reheat in the oven and you get a lovely non-soggy crunch crumble!

Personally I'm not keen on oats in crumble, but I use demerara with a small amount of granulated in the mixture.