Combine the ingredients for the filling, being sure to toss the apples as you cut them with the water/vinegar mixture to prevent them from oxidizing.
Place in a baking dish.
Combine the dry ingredients for the topping, and then rub the softened butter in by hand.
Once combined evenly, spread over the crisp so that it will act as a ‘lid’ of sorts, trapping the heat and steam, and allowing the oven’s heat to do its magic.
Bake at 190° C (375° F) for 45 minutes (of course times will vary according to individual stoves) or until you see the bubbling goodness oozing from the edges of the crisp.
Cool the crisp on the stovetop until it won’t burn your tongue, and serve with ice cream, crème anglaise or any sides of your choice.