Preheat oven to 350 degrees F. Line baking sheets with parchment paper and set aside.
Place the butter and chocolate chips in a small heavy-bottomed saucepan and melt over low heat until smooth and glossy. Alternatively, you can melt the butter and chocolate in a microwave safe bowl in your microwave oven. Heat in 30 second intervals, stirring after frequently, until completely melted. Set aside
In a large mixing bowl, beat the eggs, granulated sugar, brown sugar, and vanilla bean paste with a hand mixer until pale and fluffy, about 5 minutes. You can also use a stand mixer fitted with the whisk attachment.
Mix in melted butter/chocolate mixture until it is completely combined.
Add flour, cocoa powder, baking powder, and salt to the egg/chocolate mixture. Use a rubber spatula to mix until well combined. If you are using a stand mixer, switch over to the paddle attachment and beat on low speed until a dough forms.
Cover the cookie dough tightly with plastic wrap and let it rest at room temperature for one hour.
Use a large cookie scoop to form 2-oz balls and arrange them on parchment paper lined baking sheets, about 6 cookies per sheet. Press the cookies with your fingers to flatten the top slightly and lightly press chopped hazelnuts and a couple of pieces of dark on top of each cookie dough ball.
Bake the cookies for 10-12 minutes, until edges are slightly firm and centers are still soft.
Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.