Apple crumble is forgiving, but a deep dish packed with hard apple can still produce a browned top over an undercooked middle. For a small batch, choose a modest, shallow ovenproof dish.
A starting mixture
For roughly four portions, slice 500 g peeled and cored apples. Toss with one or two tablespoons sugar, depending on their sharpness, and a little cinnamon. Put in the dish with a tablespoon of water.
Rub 60 g cold vegan baking block into 80 g plain flour, then stir in 40 g rolled oats and 40 g sugar. Scatter loosely over the fruit without pressing it into a solid lid. Bake at 180°C / 350°F for about 35–45 minutes, until the topping is golden and the apples are tender when pierced.
Let it settle briefly before serving; bubbling fruit can be much hotter than it looks. The exact sweetness depends on the apples, so taste the raw fruit while preparing it, before it touches any flour mixture.
Make the fruit and topping agree
Some apples hold their shape while others break down readily. Thin slices help a firmer variety soften before the topping overcolors. If you prefer larger chunks, a brief gentle pre-cook of the fruit can make the timing easier, though it changes the amount of liquid in the final dish.
The topping should remain loose enough for steam to escape. Pressing it firmly into a smooth layer makes a different crust and can leave a damp underside. A few larger crumbs are pleasant, provided there is not one heavy slab across the whole dish.
Let the finished crumble rest while you bring out plates and a cool accompaniment. Plain plant yogurt gives a sharper contrast than a sweet vanilla dessert. Keep that choice separate from the baking: there is no need to change the entire crumble because two people prefer different things beside it.