You will be floating in the clouds with this light and fluffy custard cake topped with pistachios and whipped cream.
3 eggs, separated
7 tablespoons plus 2 teaspoons baker's sugar, divided
2 vanilla beans, split in half lengthwise
1 cup plus 2 tablespoons Crystal sour cream
Finely grated zest from ½ an orange
Finely grated zest and juice of 1 lemon
¼ cup coarsely chopped pistachio nuts
Whipped cream for serving
Preheat the oven to 350 °F. Grease a 10-inch round cake pan, and line the base with parchment paper.
Grease the parchment paper and set aside.
In a large bowl using either a stand or electric mixer, beat the egg yolks with 5 tablespoons plus 2 teaspoons of sugar until thick and pale, about 5 minutes. Scrape the seeds from the vanilla beans and beat into the egg mixture. Beat in the sour cream, orange zest, lemon zest, and lemon juice until incorporated.
In a separate bowl, whisk the egg whites with the remaining 2 tablespoons of sugar until soft peaks form. Gently and evenly, fold the whites into the sour cream mixture. Pour the cake mixture into the prepared cake pan.
Place the cake pan in a larger pan, allowing for at least 1-inch clearance on all sides. Place the pan in the oven and pour in boiling water halfway up the filled cake pan.
Bake the cake for 20 minutes and then gently sprinkle the pistachios evenly over the top of the cake — continue baking until the top of the cake is lightly browned, about 20 more minutes. The consistency of the cake should resemble a light sponge on top with a moist custard below. Slice into 8 pieces and serve on a plate with whipped cream.