Ingredients
1 cup all-purpose flour
1/3 cup cocoa powder
1/4 teaspoon salt
8 tablespoons (1 stick) unsalted butter, softened
2/3 cup sugar
1 egg yolk
2 tablespoons milk
1 teaspoon vanilla extract
1 1/4 cups hazelnuts, chopped fine
1 egg white
14 soft caramel candies
3 tablespoons heavy cream
Instructions
With electric mixer or food processor on medium-high speed, beat butter and sugar until light and fluffy, 2 minutes.
Add egg yolk, milk, and vanilla and mix until incorporated
Combine flour, cocoa, and salt in bowl.
Reduce speed to low and add flour mixture to the wet ingredients and mix until just combined.
Wrap dough in plastic wrap and refrigerate until firm, 1 hour.
Place your oven rack in upper-middle and lower-middle positions and heat oven to 350 degrees F.
Line 2 baking sheets with parchment paper.
Whisk egg whites in bowl until frothy.
Place hazelnuts in another bowl.
Roll dough into small balls, dip in egg whites, then roll in the nuts.
Place balls 2 inches apart on prepared baking sheets.
Using the 1/2-teaspoon measure, make indentation in center of each ball.
Bake until set, about 12 minutes, switching and rotating sheets halfway through baking.
Place the caramel and heavy cream in a pot and gently heat them, stirring occasionally, until smooth.
Once cookies are removed from oven, gently re-press existing indentations (they tend to fade with baking).
Fill each with caramel mixture.
Cool 10 minutes, then transfer to wire rack
