Preheat oven to 350 degrees. Butter and flour an 8- or 9-inch springform pan
In electric mixer fitted with paddle attachment, cream butter and white sugar until pale and light, about 1 minute. Add eggs, one at a time, and beat until light and fluffy, another minute or two. Beat in vanilla.
Sift together flour, baking powder and salt. Pour dry ingredients into mixer with the lemon zest, and mix until just combined. In medium bowl, toss together apples, brown sugar and nuts. Scrape batter into the prepared pan, smooth the top, and then sprinkle with the apple mixture.
Bake until a toothpick comes out clean from the center of the cake, about 35 to 40 minutes. (My cake took 45 minutes.) Let cool on a rack, then unmold and cut into wedges. Serves 8
Sprinkle with powdered sugar.
NOTE: I used tart Granny Smith apples but Golden Delicious or Honeycrisp would work beautifully, too. I do not put the