Combine cream and milk in a medium saucepan over a medium heat until it is about to simmer.

Meanwhile, whisk yolks, cornflour, vanilla and sugar together in a large heatproof bowl. Slowly pour in the hot cream mixture whilst continuing to whisk until combined.

Return mixture to saucepan and place over low heat. Cook, whisking constantly, until custard thickens and thickly coats the back of a spoon. Transfer to a large heatproof bowl. Set aside to cool slightly. Cover surface with plastic wrap. Refrigerate until thick and cold about 4 hours or overnight.

Combine flour and sugar in a bowl. Using your fingertips, rub butter in. Squeeze pieces of mixture together to form large pieces of crumble.

Mix in oats and ¼ cup of the almonds. Set aside.

Preheat oven to 160°C (fan-forced). Invert the base of a 23cm, base measuring 22cm springform pan. Grease and line base and sides with baking paper.

Beat butter and sugar in the bowl of an electric mixer until pale and creamy. Beat in eggs, one at a time, until combined. Stir in ½ cup of the custard. Add flour and milk in two batches, stirring until combined. Spoon mixture into prepared pan and smooth surface.

Dollop teaspoonfuls of remaining custard on top of cake batter then sprinkle with 1⅓ cups (140g) of the frozen raspberries. Press raspberries into custard and cake batter. Sprinkle with crumble then remaining raspberries and remaining almonds.

Bake for 1 hour and 40 minutes or until a skewer comes out clean when inserted into cake. Cover with foil when beginning to get dark on top. Stand in pan for 40 min before removing. Dust lightly with icing sugar and serve warm or room temperature with remaining custard.