Epona
Radar 2006-2020, Sonic 2006-2022, Jakey 2007-2024
If you don't want to use flour / pastry..
I use oats as a kind of crumble topping on fruit. It could be lovely on your apple and mince meat mix.
Just oats and melted butter mixed together..layered on top of the squashed apple and mincemeat and into the oven for 20 mins to crisp up the topping a little bit.
That's an excellent idea - oats or a mix of oats/seeds/nuts - toasted or as is.
A crumble type topping but without being full of processed carbs, would also work without the butter for an even healthier option.