This flavor-packed elderberry tiramisu is made with delicious tannic elderberries, blackberries, honey, mascarpone, and whipped cream.
In the bowl of an electric stand mixer fitted with the whisk attachment, beat together the egg yolks and sugar at medium speed until pale and silky smooth, about 3 to 5 minutes. Pour into a separate bowl and set aside for a moment.
Place the whipping cream in the stand mixer bowl (you don't need to clean it out after the egg yolks, it's fine if there's some residue), and beat at medium speed until the mixture holds soft peaks, being VERY careful not to overbeat it. Add the egg yolk mixture, mascarpone, 3 tablespoons of the elderberry concentrate, and the salt to the whipping cream and beat at low speed until combined. Cover and refrigerate until you're ready to assemble.
Take a ladyfinger cookie and dip it quickly and fully in the elderberry concentrate, then place it in a rough 9 1/2 x 9 1/2-inch square baking pan. Do not hold the cookie in the liquid too long otherwise the tiramisu will get runny. Repeat until you have one layer of the cookies (you should have used about half of them). Then pour half of the mascarpone cream over the cookies and use a spatula to even it out.
Repeat the dipping process with the remaining cookies to create one more layer of cookies on top of the mascarpone, and then top this cookie layer with the remaining half of the mascarpone whipped cream. Top with the elderberry drizzle and sprinkle the pistachios on top. Refrigerate for at least 4 hour before serving, but overnight refrigeration is best to form up the shape of the tiramisu. Then serve and enjoy!