Makes 1 rectangular cake.
FOR THE TOPPING
1/3 cup light brown sugar
1/2 cup granulated sugar
1/2 cup chopped walnuts
1 teaspoon ground cinnamon
1. In a bowl, combine thelight brown and granulatedsugars.
2. Stir in the walnuts andcinnamon and mix well. Set aside.
FOR THE CAKE
Extra butter (for the pan)
2 cups flour
1 teaspoon baking powder
1/2 teaspoon baking soda
Pinch of salt
1 cup (2 sticks) unsalted
butter, at room temperature
1 1/4 cups granulated sugar
1 teaspoon vanilla extract
1 cup sour cream
2 large baking apples, peeled and sliced (see box below)
1. Set the oven at 350 degrees. Generously butter a 13-by-9-inch baking dish.
2. In a bowl, stir together the flour, baking powder, baking soda, and salt.
3. In an electric mixer, cream the butter and sugar until fluffy. Scrape down the sides of the bowl. Add the eggs, one by one, followed by the vanilla.
4. With the mixer set on its lowest speed, beat the flour mixture into the batter alternately with the sour cream, beginning and ending with flour.
5. Spread half the batter in the baking dish. Sprinkle with about 1 tablespoon of topping. Cover with apples and 1 more tablespoon of topping. Spread the remaining batter on top. Sprinkle with the remaining topping.
6. Bake the cake for 40 minutes, until a toothpick inserted into the center comes out clean.
7. Let the cake cool on a rack for 30 minutes. Cut into large squares and serve warm.