Ingredients:

  • 1 cup (226g) unsalted butter, softened
  • ½ cup (100g) granulated sugar
  • ¼ cup (50g) packed light brown sugar
  • 1 large egg yolk
  • 1 teaspoon (5ml) vanilla extract
  • 2 cups (250g) all-purpose flour
  • ½ cup (50g) finely ground toasted hazelnuts
  • ¼ teaspoon (1.25ml) salt
  • 4 ounces (113g) good-quality dark chocolate (at least 70% cocoa), finely chopped
  • ⅓ cup (80ml) heavy cream
  • 1 tablespoon (15g) unsalted butter
  • Pinch of sea salt (optional)

Instructions:

  1. Toast the Hazelnuts (if using whole): Spread hazelnuts on a baking sheet and toast in a preheated oven until fragrant and skins crack, about 8-10 minutes. Cool and rub off skins. Grind finely in a food processor.
  2. Cream Butter and Sugars: In a large bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
  3. Add Egg Yolk and Vanilla: Beat in the egg yolk and vanilla extract until well combined.
  4. Combine Dry Ingredients: In a separate bowl, whisk together the flour, ground hazelnuts, and salt.
  5. Gradually Add Dry to Wet: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.
  6. Chill the Dough: Divide the dough in half, flatten into disks, wrap in plastic wrap, and chill for at least 45 minutes (or up to 2 days). This helps prevent spreading.
  7. Preheat Oven and Prepare Baking Sheets: Preheat oven and line baking sheets with parchment paper.
  8. Shape the Cookies: Roll dough into 1-inch balls. Place on prepared baking sheets, spacing them apart.
  9. Make the Thumbprints: Use your thumb (or the back of a small spoon) to make an indentation in the center of each ball.
  10. Bake the Cookies: Bake until the edges are lightly golden brown.
  11. Cool Completely: Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
  12. Make the Chocolate Ganache: While the cookies cool, place the chopped chocolate in a heatproof bowl. In a small saucepan, heat the heavy cream until just simmering. Pour the hot cream over the chocolate and let it sit for a minute to soften the chocolate. Add the butter and salt. Whisk until smooth and glossy.
  13. Fill the Cookies: Let the ganache cool slightly until it thickens enough to pipe or spoon into the thumbprint indentations.
  14. Chill (Optional): For a firmer ganache, chill the filled cookies in the refrigerator for 15-20 minutes.