By definition, a buckle is a cake studded with fruit and capped with a crumble topping. In this one, the spiced apples settle down into the cake batter during cooking, while most of the pecan crumble mixture stays on top. Buttermilk lends extra tenderness and a delicate tang to the cake.
Note: If you don’t have buttermilk on hand, you can substitute clabbered milk: Add 1 tablespoon of lemon juice or white wine vinegar to 1 cup of whole or 2% milk and let stand for 10 minutes before using.
2 large firm-tart apples such as Granny Smith or Northern Spy (about 1 pound total), peeled, cored, and cut into 1/2-inch-thick slices
1/4 teaspoon plus 1 teaspoon ground cinnamon
1 tablespoon granulated sugar
1/2 cup firmly packed light brown sugar
1/3 cup all-purpose flour
1/4 teaspoon freshly grated nutmeg
1/2 cup finely chopped pecans
3 tablespoons cold salted butter, cut into small cubes, plus more for greasing pan
Preheat the oven to 350°, and set a rack to the middle position. Grease a baking pan. In a medium bowl, toss the apple slices with the 1/4 teaspoon cinnamon and 1 tablespoon sugar. Set aside at room temperature.
Meanwhile, in a small bowl, toss the remaining 1 teaspoon cinnamon with the brown sugar, flour, nutmeg, and pecans. Scatter the cold butter over all and use a pastry cutter or fork to work it in until the mixture looks like wet sand and the largest pieces are pea-sized. Refrigerate until ready to use.
7 tablespoons salted butter, at room temperature
3/4 granulated sugar
2-1/4 cups all-purpose flour
1-1/2 teaspoons baking powder
1/2 teaspoon baking soda
1-1/2 teaspoons kosher or sea salt
1 cup buttermilk (see Note)
1 large egg
Make the cake: Using a standing or hand-held mixer with a whisk attachment, cream together the butter and sugar in a large bowl until the mixture is fluffy, very pale, and mousselike in texture, 5 to 8 minutes. In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. In a third bowl, whisk together the buttermilk and egg. Add one-third of the flour mixture to the butter mixture. Mix briefly, then add half the buttermilk/egg blend and mix again. Repeat, adding another third of the flour mixture and the remaining buttermilk/egg mixture, then finish with the remaining third of the flour mixture and stir just until combined.
Spread the batter evenly into the baking pan (it will be quite thick). Lay apple slices, overlapping slightly, over the batter in neat rows. Sprinkle the crumble topping over all.
Bake until the top is golden and a toothpick inserted into the center comes out clean, 35 to 45 minutes. Let cool on a rack for 30 minutes, then serve warm from the pan.