Apple and Blackberry Crumble with Vanilla Custard

Preheat oven to 375°F (190°C).

In a mixing bowl, combine sliced apples, blackberries, granulated sugar, and lemon juice. Toss to coat evenly.

Pour the fruit mixture into a 9-inch baking dish.

In a separate mixing bowl, combine flour, oats, brown sugar, cinnamon. Cut in cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs.

Sprinkle the crumble topping evenly over the fruit mixture.

Bake for 30-35 minutes, or until the topping is golden brown and the fruit is bubbling.

Let cool slightly before serving.

Serve warm with a generous dollop of vanilla custard.

(Optional) To make the Vanilla Custard: In a saucepan, heat the milk until just simmering. In a bowl, whisk together the egg yolks and sugar until pale and thick. Gradually whisk the hot milk into the egg yolk mixture, then pour the mixture back into the saucepan. Cook over low heat, stirring constantly, until the custard thickens enough to coat the back of a spoon. Do not boil. Remove from heat and stir in vanilla extract. Let cool slightly.