Dark Chocolate Sandwich Cookies with Mascarpone Filling
Barry is rarely content with one simple element in his desserts. Working on this recipe to cap an Italian menu, it was not enough just to serve deeply decadent, dark chocolate cookies. Inspired by cannoli, he decided upon a sandwich cookie filled with ricotta and sweet, soft Italian mascarpone cheese, vanilla, and roasted pistachios.
Make the cookies: In a stand mixer with the paddle attachment, beat the butter, granulated sugar, and brown sugar until creamy, scraping down the sides of the bowl as needed. Mix in the milk and vanilla.
In a medium bowl, thoroughly combine the flour, cocoa, salt, and baking soda. Slowly add to the butter mixture while beating on a low speed. Add chocolate chips, if using, and mix until just combined. When evenly mixed, shape the dough into a log about 2 inches thick and roll it in wax paper. Chill in the refrigerator for at least 2 hours or overnight.
Preheat the oven to 350 degrees F.
Use a sharp knife to slice the cookies into 1/3-inch-thick disks. Don't worry if cookies break apart as you cut them--pieces can be stuck back together and will bake fine. Arrange 2 inches apart on baking sheets lined with parchment paper. Bake until set, 10 minutes. Cool for a few minutes on the baking sheets, and then remove to racks to cool completely.
Make the filling: Set aside half of the chopped pistachios for garnish. Mix the remaining pistachios with the confectioners' sugar, mascarpone cheese, ricotta, vanilla, and salt until just blended; do not overbeat, as the mascarpone will get too thick. Cover and refrigerate until needed.
To assemble, put a scoop of filling on the bottom side of a cookie and top with the bottom side of another cookie, so that there is about 1/4 inch of filling in each sandwich. Coat the filling edges with the reserved pistachios.
These cookies are best assembled as close to serving time as possible, or else they lose their crispness.