Creamy Blueberry Custard Cake

Remove from the heat and whisk in the butter until the custard is glossy and smooth. Transfer to a bowl and cover with plastic wrap pressed directly onto the surface to prevent a skin from forming. Let it cool while you prepare the cake.

Make the cake batter: In a large bowl, whisk together the canola oil, egg, yogurt, vanilla extract, and lemon zest. Add the flour, baking powder, and salt, then whisk until just smooth.

Remove 1/3 cup of the batter (this can be baked separately in a greased ramekin for 25 minutes as a tester). Pour the remaining batter into the prepared springform pan and smooth the surface.

Assemble the topping: Whisk the cooled custard until smooth. Dollop half of it over the cake batter and spread it toward the edges. Scatter half of the blueberries on top.

Fold the remaining blueberries into the rest of the custard, then spread this mixture over the cake. Press the blueberries down slightly to ensure a flat surface.

Bake for 35 minutes. Briefly remove the cake from the oven and use two small knives to gently burst some of the blueberries on the surface to release their juices. Bake for a further 10 minutes.

Allow the cake to cool completely in the pan for about 3 hours. Once cooled, refrigerate the cake (still in the pan) for at least 12 hours to allow the custard to set properly.

Remove the cake from the pan and slice. For the best texture and flavor, allow the slices to sit at room temperature for a few minutes before serving.