Flourless chocolate cake with whipped sour cream

Melt the unsalted butter and the bittersweet chocolate together in a 10 inch nonstick pan over low heat, then turn off the heat.

Crack six large eggs and separate the yolks from the whites.

Whip the whites by hand to the soft peak stage, about six minutes, or 30 to 40 seconds in a stand mixer. Do not overwhip.

To the yolks add the buttermilk, sugar, cornstarch, salt, vanilla extract and the coffee.

Make sure the butter is fully mixed into the chocolate with no visible fat on top, then add it to the yolks and stir to combine.

Stir the whipped whites in rather than folding, then the batter is done.

Line a nine inch springform with a round of parchment and spray very liberally with pan spray.

Pour in the batter and pound the pan a few times on the counter to knock out air voids and level it.

Bake in a preheated 275F oven for 50 to 60 minutes, until it just barely jiggles in the middle. A cake tester will not come out clean.

After 10 to 15 minutes out of the oven, run a paring knife around the edge, pop the springform open and lift off the ring.

Cool about 30 minutes, then refrigerate one to two hours to fully set.

Whisk the heavy cream with the powdered sugar three to four minutes until it holds some air and makes soft peaks.

Add the sour cream and whisk another 30 seconds until slightly thicker but still a touch loose and saucy, not stiff.

Set the chilled cake on a large square of parchment and dust the top with dark cocoa powder through a strainer.

Cut with a thin sharp knife warmed in a jar of warm water, cleaning and rewarming the blade between each cut.

Plate a slice, add a thick dollop of the whipped sour cream, scatter toasted chopped hazelnuts, drizzle with olive oil and sprinkle with flaky salt.