This is one of my favorite fall cakes to make, and it’s all about the combination of soft juicy apples and that crunchy buttery crumb on top. Over the years I figured out one little trick that makes all the difference: I don’t add the streusel right away. I wait until the cake has already baked for 20 minutes, then sprinkle it on. That way it stays right on top, golden and crumbly, instead of sinking down into the batter the way it does when you add it too early.
For the batter:
- 3 eggs
- ½ teaspoon salt
- 1 cup granulated sugar (you can reduce to ¾ cup if your apples are sweet)
- 1 teaspoon vanilla extract
- ⅓ cup plus 2 tablespoons vegetable oil
- ⅓ cup plus 1 tablespoon sour cream
- 2 cups all-purpose flour
- 1 heaping teaspoon baking powder
For the filling:
- 3 large apples
- 1 teaspoon ground cinnamon, optional
For the streusel:
- ⅓ cup all-purpose flour
- 2 tablespoons plus 1 teaspoon granulated sugar
- 2 tablespoons cold unsalted butter
- 1 teaspoon vanilla extract, optional
Separate the eggs into whites and yolks. Add the salt to the whites and beat them with a mixer until you get a light foam. Gradually add the sugar and vanilla, beating until you have a thick, stable, glossy meringue.
Add the yolks one at a time, folding gently after each. Pour in the oil and the sour cream and mix until smooth and even.
Combine the flour with the baking powder and sift it in. Add the dry ingredients to the egg mixture in a few additions, folding gently from the bottom up each time so the batter stays airy and light.
Peel and core the apples and cut them into small pieces. If you like, toss them with the cinnamon.
Pour a little more than half the batter into a lined and greased 9-inch pan. Spread the apples evenly over the batter, then cover them with the rest of the batter. Give the pan a gentle shake so the batter settles into the gaps between the apple pieces.
Put the cake into a preheated 350°F oven and bake for 20 minutes.
While it bakes, make the streusel. Combine the cold butter with the flour, sugar, and vanilla, and rub everything together quickly with your fingers until it forms coarse crumbs.
After 20 minutes, carefully take the pan out and sprinkle the streusel evenly over the top of the cake. Return it to the oven and bake for another 20 minutes or so.
Check it with a toothpick, it should come out dry from the center. Let the cake cool in the pan, then carefully transfer it to a plate. It comes out soft and tender inside with a gorgeous golden crumb on top that stays right where it belongs.
