For the syrup, boil the sugar, water and lemon slices over high heat. Then add the molasses and let it cool. Take butter, tahini, olive oil, eggs, yogurt, baking powder and vanilla in a bowl and add flour little by little and mix. After adding the chopped walnuts, knead with your hands to obtain a smooth and soft dough. Spread the dough that you opened with your hands in the thickness of a finger on the greased baking tray. Cut 7 cm squares, add walnut kernels in the middle and rest for 30 minutes. Bake in the oven heated to 140 degrees for 45 minutes and make the oven temperature 160 degrees and bake for another 10 minutes. Remove from oven and let stand for 10 minutes. Pour the warm syrup over the nevzine and serve after it has cooled.