I wanted a dessert I could make well ahead of a dinner, and also one that featured both white and dark chocolate, plus hazelnuts. The results of my brainstorm are a tart shell that remains stable at room temperature for more than a month, and once filled, a tart that can be refrigerated for up to three weeks. The shell is candy like, the filling is a simple ganache which could no doubt be gussied up with liqueur or other flavoring or decorated with raspberries or strawberries. I’m going to give you a range for the crust ingredients because you might want to make tartlets or cookies with the extra and you might like a thicker crust or your pan might be 9 or 10 inches in diameter. One issue I had when cutting the tart (8″ serves 12) is that when the crust is thinner (as in photo above) the side can break off. This didn’t happen all the time, but it did happen, and I haven’t figured out how to fix it other than making a thicker crust which to me is not as aesthetically appealing. (Update: the last time I made this I put the crust only on the bottom of the springform pan, using 2 ounces each of chopped hazelnuts and crisp rice, plus 5 ounces of white chocolate. I expect to be able to run a knife around the perimeter of the springform to release the tart–which is really more like candy. You can pick up a piece like a bon-bon.)
For the crust, coarsely chop 8-10 ounces of toasted, (preferably skinned), hazelnuts and combine with 2-4 ounces of crisp rice cereal. I used Trader Joe’s rice cereal, and I wanted a slightly more salty crust, so I added a few grinds of sea salt. Melt 8-10 ounces of good quality white chocolate (made with cocoa butter) and stir in the nuts and rice crisp. See the first photo.
Press the sticky mixture into a straight-sided springform or tart pan (8″-10″ again, I’m giving you a range) that you have not only greased but also lined the bottom with greased parchment. Use a glass to very firmly press the mixture against the sides and to the bottom of the pan. You have about 25 minutes before the chocolate hardens. This is sticky work, so grease your fingers and be patient.
For the filling, I use a 50/50 ganache of half 72% bittersweet chocolate and half heavy cream. I heat the cream and chopped chocolate in a microwave for one minute, then stir (and perhaps heat again for 15 second intervals) until smooth and well combined. 8-10 ounces of chocolate and cream will fill an 8-10 inch tart shell. Chill the tart before unmolding so that it is firm and easier to handle.
Once the tart is filled it needs to be refrigerated for longer storage, but it’s also fine held at room temperature for 4-6 hours. I think it tastes better when it’s not so cold. I think it could also be frozen, but the components are so stable and easy to make ahead, you don’t need this extra step. Total work time is less than 20 minutes!