Coffee Hazelnut Crumble Cake Makes one 8-inch cake ⸻ Hazelnut Crumble Ingredients * 100g all-purpose flour * 50g brown sugar * 50g granulated sugar * 40g melted butter * 60–70g chopped toasted hazelnuts * Pinch of salt * Optional: ½ tsp cinnamon ⸻ Cake Batter Ingredients * 145g melted unsalted butter * 120g granulated sugar * 100g dark brown sugar * 2 large eggs * 315g all-purpose flour * 7g baking powder * 3g baking soda * 2g salt * 60ml strong coffee or espresso, cooled * 120ml buttermilk * 35g Greek yogurt * 12g vanilla extract * 70g finely chopped toasted hazelnuts ⸻ Coffee Drizzle Ingredients * 40g dark brown sugar * 20g granulated sugar * 2 tbsp strong coffee * 1 tbsp butter * Pinch of salt * Vanilla (optional) ⸻ Method 1. Preheat oven to 175°C. Line an 8-inch cake pan. 2. Toast hazelnuts for 8–10 minutes and chop. 3. Make crumble by mixing all crumble ingredients until crumbly. Chill. 4. Whisk flour, baking powder, baking soda, and salt. 5. In another bowl, whisk...