Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x5-inch loaf pan.
Mix all-purpose flour, whole wheat pastry flour, baking powder, baking soda, cinnamon, and salt together. Add apple and halva.
Whisk melted butter, eggs, buttermilk, brown sugar, tahini, and vanilla extract together in another bowl. Fold into the flour mixture.
Pour batter into the prepared pan. Sprinkle turbinado sugar on top.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 45 minutes. Tent with foil after 30 minutes to prevent over-browning.
Cool in the pan for 5 to 10 minutes before inverting onto a wire rack to cool completely.
