Chocolate Thumbprint Cookies

For the Cookie Dough

• 1/2 cup (1 stick; 113 g) butter or margarine, softened
• 2/3 cup (133 g) granulated sugar
• 1 large egg, separated
• 2 tablespoons (30 ml) milk
• 1 teaspoon vanilla extract
• 1 cup (125 g) all-purpose flour
• 1/3 cup (about 28 g) unsweetened cocoa powder
• 1/4 teaspoon salt
• 1 cup (about 115 g) chopped nuts, such as pecans or walnuts

For the Filling

• 1/2 cup (60 g) powdered sugar
• 1 tablespoon (14 g) butter or margarine, softened, for the filling
• 2 teaspoons (10 ml) milk, for the filling
• 1/4 teaspoon vanilla extract, for the filling

For the Topping

• About 26 milk chocolate kisses or HERSHEY’S HUGS, pecan halves, or candied cherry halves

Instructions

1. In a medium bowl, beat the softened butter, granulated sugar, egg yolk, milk, and vanilla until fluffy. In a separate bowl, stir together the flour, cocoa powder, and salt. Gradually beat the dry mixture into the butter mixture until blended.
2. Cover the dough and refrigerate for at least 1 hour, or until firm enough to handle.
3. Heat the oven to 350°F (175°C). Lightly grease a cookie sheet. Shape the chilled dough into 1-inch balls. Lightly beat the egg white in a small bowl. Dip each ball in egg white, roll it in chopped nuts, and place it on the prepared sheet. Press a thumb gently into the center of each cookie.
4. Bake for 10 to 12 minutes, or until the cookies are set. Meanwhile, beat the powdered sugar, softened butter, milk, and vanilla until smooth to make the vanilla filling.
5. Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack. Spoon about 1/4 teaspoon vanilla filling into each thumbprint. Gently press a chocolate kiss, pecan half, or candied cherry half onto each cookie. Cool completely.