Preheat the oven to 160 °C (top/bottom heat).
Grind the nut mixture and half of the toasted hazelnuts in a food processor or chop finely with a knife. Roughly chop the chocolate. Mix the chopped nuts and chocolate with the flour, sugar, cocoa powder, gingerbread spice, baking powder, baking soda and salt, then stir in the oil, plant-based milk and apple puree and mix quickly to form an even batter.Brush four ovenproof glasses with a capacity of around 200 ml with a thin layer of the remaining oil, fill half full with the batter, top with the remaining roasted hazelnuts and bake for 25 minutes. Then leave to cool completely.
Tip: The brownies can also be baked the day before. They taste even better.