Preheat your oven to 350°F (175°C). Spread the hazelnuts on a baking sheet and toast for 10-12 minutes until fragrant and golden brown. Allow to cool and chop roughly.

In a mixing bowl, whisk together the all-purpose flour, cocoa powder, baking powder, and salt until well combined.

In a separate bowl, beat the softened unsalted butter with granulated sugar and brown sugar for about 2-3 minutes until light and fluffy.

Add the egg and vanilla extract to the creamed mixture, mixing until smooth. Gradually stir in the dry ingredients, then fold in the toasted hazelnuts.

Using a cookie scoop, scoop the dough into balls, flatten slightly, and place on a lined baking sheet, leaving space between each cookie.

Bake for 10-12 minutes until edges are set; centers should be soft and chewy. Cool on a wire rack.

Melt the semi-sweet chocolate with coconut oil until smooth. Dip cooled cookie halves into the melted chocolate, sprinkle with reserved chopped hazelnuts, and let cool until set.