Nutella Thumbprint Cookies

Bahan-bahan (24 porsi)

• 1 cup all purpose flour
• 1 cup powdered sugar
• ⅓ cup unsweetened cocoa powder
• ¼ teaspoon salt
• ½ cup (1 stick) butter, (softened)
• 2 large egg yolks
• ½ teaspoon vanilla extract
• ⅔ cup Nutella ((or another chocolate hazelnut spread))