Preheat your oven to 180°C (350°F). Line a baking tin with parchment paper.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, and salt.
Add the applesauce and hazelnut milk, stirring until you get a smooth batter.
Pour the batter into the prepared baking tin.
Sprinkle crushed hazelnuts over the top and drizzle with hazelnut butter.
Bake for 25-30 minutes, until the cake is set but still slightly soft in the center.
Let it cool slightly before drizzling with melted dark chocolate.
Enjoy warm or cold, with a scoop of vanilla ice cream if you’re feeling extra indulgent!