01 -
In a medium saucepan, combine egg, sugar, and cornstarch. Stir in milk and heat over medium-low while whisking constantly until frothy. Once it begins to bubble, cook for 5-10 minutes, continuing to whisk. Remove from heat, add vanilla extract, and stir well. Set aside.
02 -
Preheat oven to 350˚F. Peel and core apples, then cut into large diced pieces. Toss apple pieces in a medium bowl with lemon juice.
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, mixing together. Sift flour and baking powder into the wet ingredients, blending until just combined. Scrape down the bowl sides as needed.
04 -
Fold apple pieces into the batter and pour into a 9-inch tart or pie pan lined with parchment paper.
05 -
Transfer the custard topping into a Ziploc bag and cut a small corner off, or use an icing bag. Starting from the center of the cake, pipe the custard into a swirl pattern outward. Repeat until all custard is used.
06 -
Bake for 30 minutes or until the top is golden brown. Cover with foil partway through baking if the top browns too quickly.
07 -
Allow cake to cool for at least 1 hour at room temperature before removing it from the pan. To remove, gently cover the top with a flat plate or cookie sheet, flip upside down to remove parchment paper, and then return to the original upright position. Sprinkle with sifted powdered sugar and cut into 8-12 slices.