A very rich and satisfying cake, with good apple flavor and just a hint of lemon. I think you will find it quite delicious.
For the filling, take 4 large apples, core, peel and slice thinly (about 7-8 cups sliced apples). Melt about 1/4 cup butter in a large pan and add the apples. Fry gently until the apples begin to give off a bit of juice. Add 1/3 cup dark brown sugar and the strained juice of a lemon. Cook until most of the juice has evaporated and there is a thick syrup, then add 1 tsp. cinnamon, 1/4 tsp. each ginger, cloves, nutmeg and allspice or just use a teaspoon and a half of prepared apple pie spice. Stir well and continue to cook until the apples are nearly dry. Set aside to cool to room temperature.
While the apples are cooling, make the crumb topping. Melt 1/4 cup butter and pour over 3/4 cup flour and 3/4 cup sugar mixed together with a sprinkle of cinnamon. Stir with a fork until you have coarse crumbs. Set aside.
Next make the cake batter:
In a large mixing bowl combine the following:
3 cups flour
1 cup sugar
1 tsp. baking powder
1 tsp. baking soda
1/2 tsp. salt
the grated rind of one lemon
Next cut into the dry ingredients 1 cup of butter cut into small pieces. Blend until it makes coarse crumbs. Now beat in 1 1/2 cup buttermilk/sour milk, 2 eggs and 1 tsp. vanilla extract.
Spread half of the batter in the bottom of a greased 9x13 inch cake pan. Spread the cooked and cooled apples evenly over the layer of cake batter. With a tablespoon or small scoop, top the apples with spoonfuls of the remaining batter. Sprinkle the crumb topping evenly over the top. Bake at 350 degrees for 45-60 minutes or until nicely browned and a toothpick stuck in the center of the cake comes out clean. Cool completely before cutting and serving. Enjoy!
For something a bit different, replace the white sugar in the cake batter with dark brown sugar and add some of the same spices used in apples with the other dry ingredients.
For a different filling, cook dried apricots or peaches in water until very tender and thick. Sweeten to taste and add your favorite spices, maybe just cinnamon and a pinch of cloves. Also add the strained juice of one lemon to the cooking water or cook in orange juice. If necessary mash the cooked fruit up a bit, you would want to have a thick puree and not be the least bit runny/watery. You will need about 2-3 cups of cooked fruit. If you use the apricots, I would also add about 1/2 tsp. almond extract to the cake batter.