Chocolate-Caramel Sandwich Cookies

• For the Cookies
• 10 tablespoons (1 1/4 sticks) unsalted butter, room temperature
• 1 1/3 cups granulated sugar
• 1 large egg yolk
• 1 1/2 cups all-purpose flour, (spooned and leveled)
• 1/2 cup cocoa powder
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon coarse salt
• For Frosting
• 1/4 cup Caramel Sauce, cooled
• 3/4 cup (1 1/2 sticks) unsalted butter, room temperature
• 1 1/2 cups confectioners' sugar

Directions

1. Preheat oven to 375 degrees, with racks in upper and lower thirds. In a large bowl, beat together butter and sugar with a wooden spoon or electric mixer until pale and fluffy; stir in egg yolk.
2. In another bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt; stir flour mixture into butter mixture until a dough forms. Drop dough by level teaspoons, 1 inch apart, onto two parchment-lined baking sheets.
3. Bake until cookies are puffed and cracked, about 8 minutes, rotating sheets halfway through. Remove sheets from oven and tap firmly on a counter to flatten cookies. Transfer cookies to wire racks and let cool completely. (To store, keep in an airtight container, up to 3 days.)
4. Make frosting: In a bowl, beat together caramel and butter with a wooden spoon until smooth; gradually beat in confectioners sugar until smooth. Spread frosting on flat sides of half the cookies and top with remaining cookies.

TIPE:  The caramel frosting can also be used for a chocolate layer cake.

Caramel Sauce

• 1 cup sugar
• 6 tablespoons (3/4 stick) cold unsalted butter, cubed
• 1/2 teaspoon coarse salt
• 1/2 teaspoon vanilla extract
• 1/2 cup heavy cream

Directions

1. In a medium saucepan, heat sugar over medium-high until melted and brown at edges, 3 minutes. With a heat-resistant spatula, pull melted sugar toward center until all sugar is melted and caramel is deep amber in color, 3 minutes more.
2. Immediately whisk in butter, coarse salt, and pure vanilla extract (take care as mixture is extremely hot and will bubble).
3. Whisk in heavy cream.
4. Pour into a heatproof container and let cool.