1 1/2 cups unsalted butter, cut into small cubes
1 1/2 pounds bittersweet chocolate, chopped into small pieces
1 cup macadamia nuts*, toasted and coarsely chopped
8 large eggs, at room temperature
Powdered sugar for dusting and sweetened whipped cream for serving
Preheat the oven to 400°F (205°C). Grease a 9 1/2-inch springform cake pan with butter and line the bottom with a round of parchment paper.
Melt butter and chocolate in a large bowl over hot water. Stir with a wooden spoon until smooth and free from lumps; set aside.
Using an electric mixer, beat the eggs until a ribbon forms when you lift the beater. Fold the eggs into the chocolate mixture and then immediately add in the chopped macadamia nuts, mixing well.
Pour the batter into the prepared springform pan and bake in the preheated oven for 45 minutes. If the cake appears to be getting too dark on top, drape pieces of aluminum foil over it and continue baking until the cake begins to feel firm in the center.
Remove from oven and cool pan on a rack. When the cake is cooled, loosen the cake by running a knife around the sides of the pan and remove the sides of the springform pan. Invert the cake onto a serving plate, lift off the bottom of the springform pan and peel away the parchment paper. Turn the cake onto a serving plate. Dust top with powdered sugar and serve cake with whipped cream.
*Pistachio nuts or walnuts can be substituted to macadamia nuts.