The only real bit of work in this is making the crumble, but the crumble topping is worth it.
You can really use whatever kinds of nuts you want (well, practically -- almonds or peanuts probably wouldn't work because of their distinctive flavours.) If you don't have a food processor, you can grind the nuts the old fashioned way: between two folds of waxed or parchment paper and you squish them with a rolling pin. Then you would just mix them into the flour. If it comes to this, though, you may wish to just buy the nuts already ground -- some problems are meant to be bypassed rather than solved. If you have celery on hand, a stalk (chopped) is nice to add to the veg mixture.