blackberry and apple kuchen

this is a german cake that is served for dessert or breakfast and it is wonderful!  it is a little difficult and time consuming but definitely worth it.  Imperial Sugar makes a turbinado sugar that works great in this recipe.  if you are making this for dessert, serve it with Whipped cream or Ice Cream.

For the cake base:
2 1/4-2 2/3 cups all-purpose flour
1/2 teaspoon of salt
2 tablespoons of sugar
Rapid yeast (about 1 teaspoon)
2 eggs
1/2 teaspoon of vanilla extract
Grated zest of half a lemon
1/4 teaspoon of ground cinnamon
1/2 cup of lukewarm milk
1/4 cup of butter, softened

For the topping:
1 egg beaten with a tablespoon of cream and a pinch of ground cinnamon
1 small or 1/2 medium-firm, tart apple
1 2/3 cups of blackberries
Zest of 1/2 a lemon
1/3 cups of self-rising flour
2 tablespoons of ground almonds
1/4 teaspoon of ground cinnamon
1/4 cups of cold unsalted butter, diced
2 tablespoons of granulated sugar
2 tablespoons of demerara sugar
2 tablespoons of flaked almonds

1. Put 2 1/4 cups of the flour in a bowl with the salt, sugar and yeast. In another bowl, beat the eggs and add them (with the vanilla extract, lemon zest and cinnamon) to the lukewarm milk. Stir the liquid ingredients into the dry ingredients to make a medium-soft dough, being prepared to add more flour as necessary. I generally use about 2 1/3 cups in all, but I advise you to start off with the smaller amount--just add more as needed. Work in the soft butter and knead by hand for about 10 minutes, when the dough is ready, it will appear smooth and springy.
2. Cover with a kitchen towel and leave till doubled in size (an hour to an hour and a quarter). Or, leave it to rise slowly in a cold place overnight. Then punch down and press to line a jellyroll pan measuring 13 by 9 inches. You may think it's never going to stretch to fit, but it will, although you may need to let it rest for 10 minutes or so mid-stretch, especially if the dough has had a cold rise. When it's pressed out on the pan, leave it to rest for 15-20 minutes and then brush with the cream and egg mixture.
3. Meanwhile, preheat the oven to 400° F. Peel and chop the apple and toss it in a bowl with the blackberries and the zest of the other half lemon. Set aside in the bowl for the few minutes it takes to make the crumble topping. Put the flour, ground almonds and cinnamon in a medium-size bowl, stir to combine and then add the cold, diced butter. Using the tips of your fingers--index and middle stroking the fleshy pads of your thumbs--rub it into the flour. Stop when you have a mixture that resembles clumpy oatmeal (this is a very buttery mixture). Fork in the sugars and flaked almonds.
4. Tumble the fruit over the egg-washed dough and then sprinkle the crumble on top of that. Put in the oven for 15 minutes and then turn down to 350° F and cook for a further 20 minutes or so, until the dough is swelling and golden at its billowing edges, and the crumble is set--don't expect it to be crunchy. Remove from the oven and, if you can, wait five minutes or so before cutting it into greed-satisfying slabs.