Chocolate Hazelnut Thumbprint Cookies 

Ingredients:

2/3 cup (165 g) unsalted butter, softened
2/3 cup (140 g) caster sugar
1 1/2 tsp vanilla extract
2 egg yolks
2/3 cup (133 g) dark chocolate, melted
1 1/4 cups (187 g) all-purpose flour, sifted
1/3 cup (30 g) cocoa powder, sifted
1/4 tsp salt
1 cup (125 g) hazelnuts, toasted and finely chopped
1/2 cup (150 g) chocolate hazelnut spread (like Nutella)
Instructions:

Preheat the Oven:
Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Make the Cookie Dough:
In a large bowl, cream together the softened butter and caster sugar until light and fluffy.
Add the vanilla extract and egg yolks, mixing until well combined.
Stir in the melted dark chocolate until fully incorporated.
Gradually add the sifted flour, cocoa powder, and salt, mixing until a dough forms.
Shape the Cookies:
Roll the dough into 1-inch balls and then roll each ball in the finely chopped hazelnuts to coat.
Place the balls on the prepared baking sheet, leaving space between each cookie.
Using your thumb or the back of a spoon, make an indentation in the center of each cookie.
Fill with Hazelnut Spread:
Bake the cookies in the preheated oven for about 10-12 minutes.
Remove from the oven and immediately fill each indentation with a small amount of chocolate hazelnut spread.
Cool and Enjoy:
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.