Buttery, shortbread-like thumbprints, potent with cocoa, dusted with chopped walnuts, and filled with rich, luscious semi-sweet chocolate ganache! These Walnut Chocolate Thumbprint Cookies are simple, elegant, and unforgettable!
In a large mixing bowl, combine butter and sugar. Cream until light and fluffy.
Beat in egg yolk, milk, and vanilla.
In a medium bowl, whisk together flour, cocoa, and salt.
Add dry ingredients to the wet ingredients in the mixing bowl, and beat until just combined.
Refrigerate for 1 hour or until dough easily forms into a ball.
Shape into 1-inch balls, and roll in walnuts.
Arrange 2 inches apart on parchment paper or silicone mat-lined baking sheets.
Press an indentation in the center of each cookie using your thumb or the end of a wooden spoon.
Bake at 350 degrees for 10-12 minutes, or until set when you lightly touch an edge (carefully).
Remove cookies to wire racks to cool completely.
In a small microwave-safe bowl, combine chocolate, heavy cream, and butter.
Microwave on high for 30-seconds, stir, and microwave for 15-second intervals until chocolate is melted and the mixture is smooth.
Spoon into the center of each cookie, and allow to set.