WALNUT CAKE

Steps:

• Heat oven to 375 degrees Fahrenheit/190 degrees Celsius. Grease an 8-inch/20-centimeter springform pan with oil or butter. Line the bottom of the pan with parchment paper and set aside.
• Place egg yolks and muscovado sugar in the bowl of a stand mixer fitted with the whisk attachment (or in a large bowl, if using a hand-held electric mixer). Whip on high speed for about 2 minutes, or until pale and fluffy, scraping down sides of bowl as necessary. Transfer mixture to a large bowl. Add walnuts, lemon zest and salt and mix well to combine.
• Clean and dry the stand mixer bowl and whisk attachment, then add egg whites to bowl. Whip on high speed for 2 minutes, or until stiff peaks form. Using a spatula, fold egg whites into the walnut mixture a third at a time; the mixture will be thick and quite difficult to bring together at first but will gradually loosen, so the final addition of whites lightens the batter considerably.
• Pour batter into pan and bake for 40 minutes, until evenly puffed. This is a moist cake, so a skewer inserted inside should not come out completely dry and clean. Let cake cool for 5 minutes, then release it from the pan. (You may need to run a small knife around the edge.) Carefully flip over cake, remove pan bottom and paper, and flip again to transfer it to a large plate. Brush surface with amaretto and then leave to cool completely.
• While cake is cooling, make the caramelized walnuts: Sprinkle sugar evenly over the bottom of a medium saucepan and place over medium heat. Cook gently for about 6 minutes, swirling pan but resisting the urge to stir, until you get a medium brown syrup, the consistency of maple syrup. Add walnuts and quickly stir them into the syrup until coated. Pour nuts onto a parchment-lined sheet pan, spread in a single layer, and sprinkle with a pinch of salt. Once cool and hardened, roughly chop into 1/2- and 1-inch/1- and 2-centimeter pieces.
• To serve: Add cream and sugar to the bowl of an electric stand mixer fitted with the whisk attachment (or use a large bowl and a hand-held whisk). Whip on high speed for 1 minute, or until firm and fluffy. When cake has cooled, spread cream over surface and then scatter with caramelized walnuts.