Step 1

Preheat the oven to 160°C (320°F). Spread hazelnuts on a baking tray and toast for 7 - 8 minutes until lightly browned and fragrant. Remove from the oven and place nuts in a clean tea towel and gently rub together until the skin comes off partially. Once cooled, coarsely chop the hazelnuts on a cutting board. Set aside.

Step 2

In one bowl combine plain flour, cocoa powder, baking powder and salt.

Step 3

In a large bowl whisk together sugar, melted butter, egg yolk, vanilla bean paste and grated citrus zest.

Step 4

Fold the dry ingredients into the wet ingredients stirring just until combined. Add chocolate chunks and chopped hazelnuts until everything mixed. Keep the dough in the fridge for about 30 minutes.

Step 5

Using a tablespoon scoop the dough into balls of the size of large walnuts and arrange them on a baking tray, leaving 2 - 3 cm between each ball.

Step 6

Bake in the oven for 7 - 8 minutes or until the edges are set and the tops are dark and shiny. Remove from the oven and allow cookies to cool on the baking tray for 3 minutes before transferring to a wire rack to cool completely.