Peel and grate quince. Along with 100 g of sugar and 50 g butter quince cook until tender. Peel and grate the apples and add to cool quince mixture. Flavored with vanilla, cinnamon and lemon zest. Total fruit mixture should be about 2 cups of latte macchiato - Clean the cream 800 ml the feta cheese with a spoon and add to it, spoon by spoon, stirring the apple mixture. Divide fruit mixture in two. Beat the eggs with sugar, add the oil and melted 50 g butter. Add 350 g of flour mixed with baking soda. Finally, add half of the fruit mixture. Stir with a spatula or spoon. Pour into a rectangular greased with sunflower oil and sprinkled with flour onto a baking tray or paper. To the other half of the fruit mixture, add spoon by spoon 100 g flour, stirring well. Beat 3 egg whites with 100 g of sugar, add half tsp kremotartar limontozu or until a dense but not air mass. Gently mix the two mixtures with a spatula or spoon. Lightly roast and grind in large pieces the walnuts. Sprinkle the walnuts on egg - fruit mixture in the tray. On the walnuts pour egg white - fruit mixture evenly and smooth. Bake at 160 C - in preheated oven for 50 -60 minutes. If necessary, during baking, cover the top with aluminum foil or paper not to burn the cake. After baking, allow the cake to cool, cut into rectangles or rhomboids and sprinkle with powdered sugar.