1 cup (2 sticks) unsalted butter, room temperature
1 large egg
2 teaspoons pure vanilla extract
1/4 cup creme fraiche
3 tablespoons hot water
10 ounces semisweet chocolate, coarsely chopped
4 tablespoons unsalted butter, cut into pieces
1 cup plain malted milk powder
3 ounces cream cheese, room temperature
6 tablespoons half-and-half
1 teaspoon pure vanilla extract
Heat oven to 350 degrees F. Line two baking sheets with Silpat or parchment paper;
Cookies: In a medium bowl, sift together the flour, cocoa powder, malted milk powder,
baking soda, and salt; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, beat the
sugar and butter together until light and fluffy.
Add the egg and vanilla extract, and beat until combined.
Add the creme fraîche, beat to combine, and then beat in the water.
Add the dry ingredients, and beat on low speed until incorporated.
Using a 1/2-ounce ice cream scoop, drop dough onto prepared baking sheets, leaving
about 2 inches between cookies.
Bake until tops begin to flatten and cookies are just barely firm in the centers,
10 to 12 minutes.
Transfer to a wire rack to cool completely.
Filling: Combine the chocolate and butter in the top of a double boiler
or a heatproof bowl set over a pan of simmering water. Stir occasionally until melted
and smooth. Remove from heat, and cool until just warm.
In the bowl of an electric mixer fitter with the paddle attachment, beat the
malted-milk powder and cream cheese on medium speed until completely smooth.
Gradually add the half-and-half, beating until combined.
Add the chocolate mixture and vanilla extract, and beat until incorporated.
Refrigerate until slightly thickened but not stiff, about 30 minutes.
Return to mixer, and beat on high speed until light and fluffy, about 3 minutes,
scraping down the sides several times.
Assemble the cookies: Use a small offset spatula to spread a generous amount
of filling on the bottom of one cookie. Press the bottom of a second cookie onto
filling, creating a sandwich.
Repeat with remaining cookies and filling.
The cookies can be stored refrigerated in an airtight container for up to 3 days.