Blueberry Crumble Custard Cake

Preheat oven to 180°C/160°C fan-forced. Grease and line the base and sides of a 6cm-deep, 10x20cm loaf pan with baking paper, allowing the paper to overhang on all sides.

Using an electric mixer, beat 100g butter and 3/4 cup sugar in a small bowl until creamy. Beat in eggs, one at a time, and vanilla until just combined. Transfer to a large bowl. Add 1/2 cup plain flour and half of the milk. Beat until just combined. Add self-raising flour, custard powder and remaining milk. Beat until just combined. Spoon into prepared pan. Smooth surface.

Place oats in a large bowl with remaining plain flour and caster sugar. Mix until well combined. Add remaining butter. Rub through using fingertips until coarse chunky crumbs form.

To make custard, whisk custard powder, sugar and milk in a medium saucepan until well combined. Place over medium-low heat. Whisk in cream. Cook, whisking constantly, for 3 minutes or until mixture thickens. (If mixture becomes lumpy, remove from heat and whisk vigorously until smooth.) Remove from heat. Add butter and vanilla. Whisk until well combined.

Spread half of the warm custard evenly over the cake batter layer. Scatter with half a punnet of blueberries. Top with remaining custard. Spread evenly. Scatter with remaining half punnet of blueberries. Top with half of the crumble. Spread evenly. Scatter with half of the second punnet of blueberries. Top with remaining crumble. Spread evenly. Scatter with remaining blueberries. Place loaf pan on a baking tray. Bake, rotating the tray halfway through, for 1 hour and 10 minutes or until lightly golden on top. Set aside for 20 minutes to cool in the pan. Serve.