Growing up in an Italian family, the holidays were always kissed with chocolate, especially when we celebrated them in Rome. We would always stop at this decades-old chocolate shop near Viale Libia, close to where my grandfather lived to stand in line to get freshly-made gianduia and torrone, studded with whole roasted hazelnuts.
When I make chocolate at home, I like to play around with textures and flavors, but to this day, the combination of chocolate and hazelnut is still my favorite.
Line an 8-by-8-inch baking pan with parchment paper. In a high-speed blender, combine the cacao powder, cacao butter, 1 cup maple syrup, 2 teaspoons vanilla and ¼ teaspoon salt. Transfer the cacao powder mixture to the prepared pan, spreading evenly; refrigerate until starting to set, about 15 minutes.
Meanwhile, in a high-speed blender, combine the hazelnut butter, remaining 2 tablespoons maple syrup, remaining 1 teaspoon vanilla, 1/8 teaspoon salt and 2 tablespoons water until smooth. Add more water, 1 teaspoon at a time, until a squeezable consistency forms. Place in a resealable plastic bag and snip ¼ inch off a corner; squeeze parallel lines onto the filling and using a knife, draw perpendicular lines alternating directions to create a swirl pattern. Refrigerate until firm, at least 2 hours or overnight.