Silky Ricotta Cheesecake Babka with a Lemon Twist

First, preheat the oven to 170°C with the top and bottom heating function, without fan assistance. In the meantime, prepare a bundt pan with a capacity of about 2-2.5 liters. Take a piece of room temperature butter and very thoroughly, using your fingers or a pastry brush, grease the entire interior of the pan, paying special attention to all the nooks and patterns. Then, add a tablespoon of flour to the pan and, turning the pan, spread it so that a thin layer covers the entire greased surface. Shake out the excess flour by turning the pan upside down and tapping its bottom. This step is crucial for the bundt to come out of the pan easily after baking.

In a large bowl, sift the all-purpose flour, potato starch, and baking powder. Sifting is very important as it aerates the dry ingredients and removes any lumps, making the batter lighter. Add a pinch of salt and mix everything together using a whisk or spoon. In a small saucepan, melt the butter over low heat and set aside to cool slightly. Wash the lemons thoroughly, blanch them in boiling water, and then grate the zest using a fine grater (only the yellow part, the white part is bitter). Squeeze the juice from the same lemons.

Now the most important part: separating the yolks from the whites. Prepare two clean and dry bowls. Carefully crack the egg in half and gently transfer the yolk from one half of the shell to the other, allowing the white to flow into the bowl below. Repeat with all the eggs. Be careful not to let even a bit of yolk get into the whites, as this will prevent them from whipping properly.

In a bowl with the egg yolks, add most of the sugar (leave about 3 tablespoons for the egg whites). Using a hand mixer on the highest speed, beat the yolks with the sugar for about 5-7 minutes. The mixture should become very light, almost white, thick, and fluffy. When you lift the mixer beaters, the dripping mixture should form a distinct ribbon on the surface that holds for a few seconds before disappearing. This is a sign that the yolks are well aerated.

Reduce the mixer speed to the minimum. Gradually add the ricotta cheese to the fluffy egg mixture while mixing, just until the ingredients are combined. Then, in a thin stream, pour in the cooled butter, vanilla extract, grated lemon zest, and lemon juice. Mix very briefly, just until the mixture is uniform. Overmixing at this stage may cause the cake to be dense.

Now it's time for the dry ingredients. Gradually add the prepared mixture of flour, starch, and baking powder to the cheese mixture in two or three batches. Gently mix using a large silicone spatula or wooden spoon, making movements from the bottom to the top. The goal is to 'tire' the dough as little as possible. Mix only until no dry flour is visible. Small lumps may remain, which is normal.

In a perfectly clean and dry bowl, start beating the egg whites with a mixer on low speed. When they begin to foam and turn white, add a pinch of salt and increase the speed to medium. When the foam thickens and becomes white (the so-called 'soft peaks'), start adding the remaining sugar, one tablespoon at a time, without stopping the beating. Finally, increase the speed to maximum and beat until the foam is very thick, stiff, and glossy. When you remove the beaters from the foam, the peak formed on them should be stiff and not droop.

Now we will combine the egg whites with the cheese mixture. Do this in three stages. First, add one third of the whipped egg whites to the cheese mixture and mix quite vigorously with a spatula. This step is meant to 'loosen' the thick cheese mixture. Next, add the second portion of the egg whites and gently fold them into the batter using the folding technique. Finally, add the last batch of egg whites and very gently, with care, incorporate them into the mixture, trying to retain as much air as possible. The finished batter should be fluffy and uniform.

Carefully transfer the prepared batter to the previously prepared pan. Smooth the top with a spatula. Place the pan in the preheated oven at 170°C and bake for about 55-65 minutes. After about 50 minutes, perform the toothpick test: insert a wooden skewer into the thickest part of the cake. If it comes out dry, the cake is ready. If there is raw batter on it, continue baking and check every 5 minutes.

Remove the baked cake from the oven and place the pan on a metal rack. Leave it in the pan to cool for about 15-20 minutes. After this time, carefully turn the pan upside down and remove the cake onto the rack. Leave it on the rack to cool completely. This is very important, as decorating a warm cake will cause the icing to run.

While the cake is cooling, prepare the glaze. Break the white chocolate into small pieces and place it in a heatproof bowl. Add the heavy cream. Prepare a water bath: bring a small amount of water to a boil in a pot, and place the bowl with the chocolate and cream on top. The bottom of the bowl should not touch the water. Stir slowly until the chocolate is completely melted and combined with the cream, creating a smooth, shiny sauce. Remove the bowl from the pot and set aside for a few minutes to let the glaze thicken slightly.

Make sure the cake is completely cool. Place it on a rack, and put parchment paper underneath to avoid a mess. Drizzle the prepared white chocolate glaze over the cake, allowing it to flow freely down the sides. Before the glaze sets, sprinkle the top with coarsely chopped pistachios. Additionally, you can decorate the cake with candied lemon peel to enhance the flavor and aroma. Leave the cake for about 30 minutes to let the glaze firm up.