01 -
In a medium saucepan, combine the egg, granulated sugar, and cornstarch. Stir in the milk and heat over medium-low until frothy, whisking constantly. Once it begins to bubble, cook for 5-10 minutes while still whisking. Remove from heat, add vanilla extract, and stir well. Set aside.
02 -
Peel, core, and dice the apples into large pieces. Toss them in a medium bowl with the juice of half a lemon.
03 -
In a large bowl, combine granulated sugar, salt, and eggs. Use an electric mixer to blend until pale and frothy. Add vanilla extract and milk, then mix together.
04 -
Sift the flour and baking powder into the wet ingredients. Blend until just combined, scraping down the sides of the bowl as needed.
05 -
Fold the diced apples into the batter. Pour the mixture into a 9-inch tart or pie pan lined with parchment paper.
06 -
Scoop the custard topping into a piping or Ziploc bag. Cut the tip off one corner and pipe a swirl of custard starting from the center outward until all custard is used.
07 -
Bake the cake in a preheated oven at 350°F (175°C) for 30 minutes, or until the top begins to turn golden brown. If the top browns too quickly, cover with foil partway through baking.
08 -
Allow the cake to cool for at least 1 hour at room temperature before removing it from the pan. Gently cover the top with a flat plate or cookie sheet, then turn the cake upside down and remove the parchment paper. Flip it back right side up, sprinkle with sifted powdered sugar, and cut into 8-12 slices.