Apple dapple cakes appear in many mid-century cookbooks and they all seem to offer some little interesting riff on the concept of a cake so moist it's basically damp. It's packed with enough apple chunks to create a rippled effect on the surface of the cake, all the better to catch puddles of a simple powdered sugar icing. This version with the addition of coffee in the batter and a buttery brown sugar glaze, tempers the sweetness of both the cake and the fruit and makes it awfully hard to stop at just one square.
Technique tip: Use a 1- to 1½-quart pan as indicated so your glaze will thicken in the given time and set up properly.
Swap option: Don't swap the light brown sugar for dark brown. The extra acid will change the texture of the cake.
For the cake:1.
Position a rack to the center of the oven and preheat to 350°F. Spray a 9- by 13-inch light-colored metal baking pan with nonstick cooking spray and line it with parchment paper.2.
In a medium bowl, whisk together the flour, baking soda, salt, cinnamon and nutmeg.3.
In the bowl of an electric mixer fitted with the paddle attachment, beat the butter on medium-high speed until creamy. Add the granulated and brown sugar and vanilla and beat until light and fluffy, about 3 minutes. Reduce the speed to medium-low and slowly stream in the oil until well blended. Beat in the eggs, 1 at a time. On low speed, spoon in half of the flour mixture. Slowly pour in the coffee. Stir in the remaining flour until the batter is smooth. Fold in the apples by hand.4.
Scrape the batter into the prepared pan and smooth evenly. Bake until the cake is deeply golden all over, begins to pull away from the sides of the pan and a toothpick inserted into the center comes out clean, 45-50 minutes. Let cool slightly in the pan, set on a wire rack.
For the glaze:
In a 1- to 1½-quart saucepan over high heat, combine the brown sugar, butter, milk and salt. Bring to a full rolling boil, stirring often and boil until you can see it has thickened slightly, 2-3 minutes, depending on your pan.
Remove the pan from the heat. Stir in the vanilla. Let the glaze cool just until it stops bubbling. Pour the hot glaze over the still-warm cake. Working quickly, use a spatula to spread the glaze so it thinly and evenly covers the entire surface of the cake.
Let the cake cool completely, uncovered, on the rack. Store any leftovers loosely covered at room temperature for up to 3 days.