Apple Custard Cake

Ingredients

• 4 to 6 apples (about 1¾ lb/800 g), peeled
• ¾ cup (102 g) all-purpose flour
• 1¼ teaspoons baking powder
• ¾ teaspoon ground cinnamon
• ¼ teaspoon fine sea salt
• ½ cup (100 g) granulated sugar
• 1 small orange, clementine, or tangerine, or 1 lemon
• 3 large eggs, at room temperature
• ½ cup (120 ml) whole milk, at room temperature
• ½ teaspoon pure vanilla extract
• 2 tablespoons (28 g) unsalted butter, melted and cooled
• Demerara or turbinado sugar, for sprinkling (optional)

Instructions

1. Center a rack in the oven and preheat to 400°F (205°C). Coat an 8½-inch loaf pan with baking spray, or butter and flour it. Line the bottom and long sides with parchment, leaving an overhang for lifting the cake.
2. If slicing the apples by hand, core them and cut them now into very thin slices that bend without breaking. A mandoline or food processor fitted with a slicing disk also works well.
3. In a large bowl that can eventually hold all the apples, whisk together the flour, baking powder, cinnamon, and salt.
4. Place the sugar in a medium bowl and finely grate the citrus zest over it. Rub the zest into the sugar with your fingertips until fragrant and slightly moist.
5. Add the eggs to the citrus sugar and whisk vigorously for 2 to 3 minutes, until pale and slightly thickened. Whisk in the milk and vanilla, followed by the cooled melted butter.
6. Pour the wet mixture into the dry ingredients and stir with a flexible spatula just until you have a smooth, thin custard-like batter.
7. Slice the apples directly into the batter if using a mandoline, stopping after every two apples to stir and make room. Continue until all the fruit is added, then patiently fold for a couple of minutes to coat as many slices as possible. There will be far more apples than batter.
8. Use a large spoon to transfer the coated apple slices to the loaf pan, allowing excess batter to drain back into the bowl. Level each layer and nudge the slices into the corners. Pour the remaining batter over the top, gently wiggle the apples, and rap the pan firmly on the counter to fill the gaps. Sprinkle with demerara or turbinado sugar, if using.
9. Bake for 50 to 60 minutes. Check after 30 minutes and tent loosely with foil or parchment if the top is browning too quickly. The cake is ready when deeply golden, set through the center, and pulling slightly from the sides when the pan is gently tugged.
10. Cool in the pan on a rack for at least 1 hour. Run a table knife around the short ends, lift the cake out with the parchment, and peel the paper from the sides. Serve slightly warm, at room temperature, or chilled, plain or with whipped cream or ice cream.