Mocha Mascarpone Icebox Cake Recipe
For the Filling: In the bowl of a stand mixer fitted with a whisk attachment, combine mascarpone, heavy cream, brown sugar, liqueur, Dutch cocoa powder, instant espresso powder, vanilla extract, and salt. Mix on low speed until relatively homogeneous, then increase to medium and whip until mixture is thick enough to hold soft peaks. Taste (preferably using a cookie scrap reserved from trimming) and adjust seasoning as needed with additional salt, espresso powder, or vanilla to taste. Resume whipping on medium speed and continue whipping until cream is thick and stiff, like a frosting. Using your reserved cookie scraps, taste filling and add more salt, espresso powder, or other flavors to taste, if desired.