Peel and chop the apples into small pieces. I used a mix of apples and needed about two and a half. Squeeze the lemon juice over the apples. In a skillet, cook the apples with the butter and sugar for 5-6 minutes. Add the cinnamon and let the mixture cool.

Next, make the custard in a separate saucepan. Whisk the eggs and sugar together. Add the cornstarch and mix until combined. Place the pan over the heat and slowly add the cold milk, stirring constantly. When the custard starts to thicken, add the orange or lemon zest and vanilla extract. Once thickened, remove from heat. Transfer the custard to a baking dish, cover with plastic wrap, and set aside.

Now, make the dough. It's similar to a pâte brisée. In a bowl, combine the flour, sugar, and baking powder. Mix with a spoon, then add the egg. Add the cold butter (from the fridge), either grated or cut into very small pieces. Using gloves, rub the mixture with your hands until it resembles wet sand.

When the dough reaches the right texture, press most of it (reserve about 1 cup) into a greased 10-inch (26 cm) springform pan or baking dish. Use the bottom of a glass to press the dough evenly into the base and up the sides as much as possible.

Mix the apples into the custard with a spoon, then pour the mixture over the dough base.

Bake in a preheated oven at 350°F (180°C) with convection for about 40 to 45 minutes, depending on your oven.