I found this recipe on Martha Stewart and it is A*M*A*Z*I*N*G. If you love chocolate malts you will love these little cookie sandwiches. The filling was amazing. In fact it makes an excellent hot fudge topping for ice cream sundaes too. YUM. YUM. YUM.
2 cups plus 2 tablespoons all-purpose flour
1/2 cup unsweetened Dutch-process cocoa powder
1/4 cup plain malted milk powder
1 teaspoon baking soda
1/2 teaspoon coarse salt
1 cup (2 sticks) unsalted butter, room temperature
1 3/4 cups sugar
1 large egg
2 teaspoons pure vanilla extract
1/4 cup creme fraiche
3 tablespoons hot water
For The Filling
10 ounces semisweet chocolate, coarsely chopped
4 tablespoons (1/2 stick) unsalted butter, cut into small pieces
1 cup plain malted milk powder
3 ounces cream cheese, room temperature
1/4 cup plus 2 tablespoons half-and-half
1 teaspoon pure vanilla extract
Preheat oven to 350 degrees. Make cookies: Sift together flour, cocoa powder, malted milk powder, baking soda, and salt. With an electric mixer, beat butter and sugar on medium-high speed until pale and fluffy. Mix in egg, creme fraiche, and hot water. Reduce speed to low; mix in flour mixture.
Space tablespoon-size balls of dough 3 1/2 inches apart on parchment paper-lined baking sheets. Bake until flat and just firm, 10 to 12 minutes. Let cool on parchment on wire racks.
Making filling: Melt chocolate and butter in a heatproof bowl set over a pan of simming water, stirring. Let cool. With an electric mixer, beat malted milk powder and cream cheese on medium speed until smooth. Gradually mix in half-and-half, chocolate mixture, and vanilla. Refrigerate, covered, until thick, about 30 minutes. Mix on high speed until fluffy, about 3 minutes.
Assemble cookies: Spread a heaping tablespoon filling on the bottom of one cookie. Sandwich with another cookie. Repeat. Cookies can be refrigerated between layers of parchment in airtight containers up to 3 days.