Ingredients

1 cup powdered sugar
1 cup softened butter
2 teaspoons milk
1 large egg yolk (use white for something else)
2 cups all-purpose flour
1/4 cup cornstarch
1 cup cashews (finely chopped)

For the Brown Sugar Filling:
3/4 cups brown sugar
2 tablespoons butter
3 tablespoons milk
1/2 teaspoon vanilla
3/4 cup powdered sugar

Directions

Heat oven to 350 F.
In a large bowl, combine the powdered sugar and butter and beat well. Mix in the milk. Add egg yolk and beat until completely combined, scraping down the sides of the bowl.

Add flour and cornstarch. Stir or knead in the cashews.

Using 1 tablespoon of dough at a time, roll into balls. Place on ungreased cookie sheet, 1 ½ inches apart. Firmly press the top of each cookie with your thumb.

Bake 10-12 minutes, or until the cookie bottoms are lightly browned. Move to a cooling rack.

Make the Filling:
In a medium pan, combine the brown sugar, butter, and milk. On medium heat, bring mixture to a boil, stirring often. Once boiling, cook for 2 minutes. Remove from heat. Whisk in the vanilla and powdered sugar until mixture is smooth.

Carefully pour into depressions on cookies. The icing sets quickly, so If you are adding cashews on top, pour 4 cookies at a time and add the cashews. Repeat until all cookies are filled. If the icing gets too thick to pour, place it back on the stove at low heat briefly, stirring constantly.

Allow cookies to cool thoroughly before serving.

Store in an airtight container.