Preheat oven to 325 degrees. Place toasted hazelnuts and brioche in food processor and pulse to a coarse crumb texture. Do not grind the nuts completely. Pour into separate bowl and set aside.
Butter the sides and bottom of 9" springform pan. Sprinkle with some of the nut mixture to coat the sides and bottom of the pan. Return excess to the bowl.
Melt chocolate in the microwave on high in 20-sec intervals, stirring each time, until just melted, being careful not to burn the chocolate. Set aside to cool slightly.
In food processor, cream butter and sugar until pale and light, approx 1 min. Scrape the sides and bottom of bowl. Add cooled chocolate, eggs, vanilla, liqueur and mascarpone and process well. Scrape bowl again and add remaining nut mixture and combine. Pour into springform pan.
Bake for 60 min until just set. The top will rise and form a cracked crust, which will deflate as the cake cools. Remove from the oven onto a wire rack and let rest in the pan for 30 min or more before dusting with cocoa and powdered sugar. If made in advance, take the torta out of the fridge 2 hr before dusting.
To decorate your own Torta Caprese, place about 2 T cocoa powder into strainer and gently sift to evenly cover cake. Discard excess cocoa and tap strainer to clean. Do not use any moisture to clean strainer or powdered sugar will clump.
Place 4 strips of cut cardstock evenly spaced across the cake. Place 2 T powdered sugar into the strainer and gently sift to evenly dust the gaps between the strips. Slowly remove strips, one by one. Tap excess sugar off strips.
Turn the cake not quite halfway and reposition all 5 strips evenly across the top. The gaps will be a bit smaller this time. Repeat dusting with powdered sugar to cover the gaps. Slowly remove strips, one by one. The final result will look like a woven diamond lattice.
* Available in your Market Bakery.
** Available in your Market Cheese Shop.