Chocolate Sandwich Cookies Filled with White Ganache

Ingredients

• 0.5 teaspoon baking soda 
• 1 large eggs 
• 1.3 cup flour all-purpose plus more for parchment)
• 0.5 cup heavy cream 
• 0.3 teaspoon kosher salt 
• 0.7 cup brown sugar light packed
• 5 tablespoon butter unsalted melted ()
• 0.8 cup cocoa powder unsweetened (spooned and leveled)
• 12 ounce chocolate white divided chopped ( and )

Equipment

• bowl
• frying pan
• baking sheet
• sauce pan
• oven
• whisk
• plastic wrap
• cookie cutter
• pastry bag

Directions

1. Make the ganache filling: Bring the cream to a boil in a small saucepan.
2. Remove from heat, and add 9 ounces white chocolate.
3. Let stand 5 minutes, covered.
4. Transfer to a small bowl, and stir until smooth. Cover and refrigerate about 3 hours (or more) until thick and spreadable. Be sure to stir often during this process it will improve the texture of the ganache. Bring to room temperature before using.Make the dough: In a large bowl whisk together flour, cocoa powder, baking soda, and salt. In a separate large bowl stir together butter, brown sugar, and egg.
5. Add flour mixture to butter mixture, and stir to combine. Knead until a dough forms. Divide dough in half and wrap each in plastic wrap; chill in the refrigerator at least 1 hour and up to 12 hours.Make the cookies: When ready to form cookies roll out each half of dough between 2 sheets of lightly floured parchment to about 1/8-inch thick.
6. Transfer to baking sheets, and refrigerate until firm, about 30 minutes.Preheat oven to 350 degrees with racks in upper and lower thirds. using a cookie cutter that’s about 2-inches wide (choose an uncomplicated shape such as round, square, heart or star), making sure you have even numbers in each for a total of about twenty-four 2-inch cookies, re-rolling and re-chilling scraps as needed.
7. Place cookies 1 inch apart on parchment-lined baking sheets, and freeze until very firm, about 15 minutes.
8. Bake until firm and fragrant, about 10 to 12 minutes, rotating halfway through.
9. Let cookies cool completely on baking sheets set on wire racks.
10. Spread or pipe (using a pastry bag and a small plain tip) the ganache filling onto bottom side of half the cookies, and sandwich with remaining cookies, pressing gently. Cookies can be stored in an airtight container at room temperature up to 1 week.Make the optional topping: Melt the remaining 3 ounces of white chocolate in a small heat proof bowl set over a pan of simmering water. Once melted drizzle or pipe (using a pastry bag and a small plain tip) the white chocolate in an attractive pattern over the tops of the cookies.