Mini Chocolate Sandwich Cookies

Ingredients

• 2 cups all-purpose flour
• 1/2 teaspoon salt
• 3/4 cup unsalted butter, softened
• 2/3 cup sugar
• 2 whole large eggs
• 2 large egg yolks
• 3 ounces fine-quality semisweet chocolate, finely chopped, melted, and cooled
• 2 ounces fine-quality bittersweet chocolate, finely chopped, melted, and cooled (not unsweetened)
• 2 large eggs
• 1 cup confectioners' sugar
• 3/4 cup unsalted butter, cut into bits
• 4 ounces fine-quality bittersweet chocolate, finely chopped (not unsweetened)

Directions

1. 1

   Make cookies:.

2. 2

   Whisk together flour and salt in a bowl until combined.

3. 3

   Beat together butter and sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 2 minutes in a stand mixer (preferably fitted with paddle attachment) or 4 minutes with a handheld. Add whole eggs, yolks, and chocolate, beating until combined. Reduce speed to low, then add flour mixture and mix until combined well.

4. 4

   Put oven racks in upper and lower thirds of oven and preheat oven to 350°F.

5. 5

   Drop 1/2 teaspoons of batter 1 inch apart on 2 ungreased baking sheets. Bake, switching position of sheets halfway through baking, until cookies are puffed up, 7 to 8 minutes total, then transfer with a metal spatula to racks to cool completely. Cool baking sheets and make more cookies with remaining dough on cooled sheets.

6. 6

   Make filling:.

7. 7

   Whisk together eggs, confectioners sugar, butter, and chocolate in top of a double boiler or a large metal bowl set over a pot of simmering water and cook, whisking, until a thermometer registers 170°F Remove top of double boiler (or bowl) from pot and set in a larger bowl of ice and cold water, then stir occasionally until cold. Remove from ice water and beat with cleaned beaters at medium-high speed until pale and fluffy, about 3 minutes.

8. 8

   Fill cookies:.

9. 9

   Spread 1/2 teaspoon filling on flat side of 1 cookie, then place flat side of a second cookie over filling to form a sandwich. Fill remaining cookies in same manner.

10. 10

    Cooks' note:.

11. 11

    Cookies keep, layered between sheets of wax paper or parchment, in an airtight container at room temperature 4 days.