These Stuffed Apples with Crumble Topping are a simple, quick and healthy, yet satisfyingly naughty tasting. This easy crumble is a perfect dessert for guests, or as a one-person treat that doesn't blow your diet out the window. Without the custard, you're looking at just 212 calories per serving. You can prepare it ahead, or just make it and put it in the oven when you're hungry.
Hollow out your apples (leaving the base of the apple intact) and brush the insides with the lemon juice using a pastry brush. In a small bowl, mix the blueberries, sugar and cornstarch. Spoon this mixture into the apples. It's ok if the blueberries stick out of the apple a little. They'll breakdown and sink a bit when they're cooking.
Next make your crumble topping. Place your butter and flour in a bowl and rub the flour into the butter using your fingertips until you have breadcrumbs. They don't have to be too small, a few bigger lumps in there adds to the texture of the crumble. Stir in the sugar, and then spoon this crumble mixture over the top of the apples. If you have any extra crumble, you can either freeze it, or you can make it on a tray along with the apples in case anyone wants extra. Place the apples in the oven and cook for about 25-30 minutes - until the crumble starts to go brown.
Whilst the apples are in the oven, make your custard. Heat your cream in a pan until scalding (don't boil it though). In a jug, mix the egg yolk, cornstarch, sugar and vanilla extract. When the cream is scalding, pour into the egg mixture in a thin stream whilst whisking all the time (if you pour it in in one go, the egg will just scramble). Once mixed together, pour back into the pan (use a clean pan if your pan has a layer of cream stuck to it), and continue to stir the custard with a whisk over a medium heat until it thickens. If it gets too thick, you can add a touch more cream. Turn off the heat.
Just before your apples come out of the oven, reheat the custard, giving it a good stir and adding a touch more cream if required. Serve your stuffed apples with the custard.