Custardy Fruit Squares

Adapted from Dorie Greenspan and Annie Levy

The original recipe is for apples, though the author notes that other firmer fruits such as pears, or even mangos can be used, and highly recommends a mix of pears and apples. Annie Levy of Kitchen Counter Culture reports that it works well with quince and recommends lightly steaming before peeling and slicing.

Other notes from the author: 

Serving: Most often I serve the squares plain, but whipped cream, crème fraîche or ice cream makes a great partner.

Storing: The cake, which is good a few minutes out of the oven or at room temperature the day it is made, can also be refrigerated, covered, for up to 2 days and served chilled.

3 medium quince, pears, or juicy, sweet apples, such as Gala or Fuji, peeled
1/2 cup (68 grams) all-purpose flour
1 teaspoon baking powder
2 large eggs, at room temperature
1/3 cup (67 grams) sugar
Pinch of fine sea salt
2 teaspoons pure vanilla extract
6 tablespoons whole milk, at room temperature
2 tablespoons (1 ounce; 28 grams) unsalted butter, melted and cooled
Confectioners' sugar, for dusting (optional)

Center a rack in the oven and preheat the oven to 400 degrees F. Butter an 8-inch square baking pan and line the bottom with parchment paper.

Slice the fruit using a mandoline, Benriner or a sharp knife, turning the fruit as you reach the core. The slices should be about 1/16 th inch thick-- elegantly thin, but not so thin that they're transparent and fragile. Discard the cores.

Whisk the flour and baking powder together in a small bowl.

Working in a large bowl with a whisk, beat the eggs, sugar and salt together for about 2 minutes, until the sugar just about dissolves and, more important, the eggs are pale. Whisk in the vanilla, followed by the milk and melted butter. Turn the flour into the bowl and stir with the whisk until the batter is smooth. Add the fruit, switch to a flexible spatula and gently fold into the batter, turning everything around until each thin slice is coated in batter. Scrape the batter into the pan and smooth the top as evenly as you can--it will be bumpy; that's its nature.

Bake for 40 to 50 minutes, or until golden brown, uniformly puffed-- make sure the middle of the cake has risen--and a knife inserted into the center comes out clean. Transfer the pan to a cooling rack and allow to cool for at least 15 minutes.

Using a long knife, cut the cake into 8 squares (or as many rectangles as you'd like) in the pan (being careful not to damage the pan), or unmold the cake onto a rack, flip it onto a plate and cut into squares. Either way, give the squares a dusting of confectioners' sugar before serving, if you'd like.