For the Lemon Curd Cheesecake, first prepare the lemon curd. Mix the lemon juice and zest with the sugar and eggs in a small saucepan and add the butter. Turn on stove top to medium heat and stir until lemon and egg mixture thickens.
Strain lemon curd through a sieve and directly cover the surface with plastic wrap to prevent the lemon curd from forming a skin and let cool completely.
Preheat the oven to 175 °C and line the bottom of a springform pan with a circle of baking paper cut to size.
Mix all the ingredients for the cake base and press them onto the bottom of the cake springform pan using the bottom of a drinking glass. Form a 2.5-inch high border.
Bake the cheesecake base on the middle rack for about 10 minutes. Let cool completely on a cooling rack.
Turn the oven down to 150° C.
Cream the cream cheese with the sugar in a bowl with a hand mixer until you can’t hear the sugar crystals scraping. On the lowest mix setting, beat in one egg at a time and finally mix in the sour cream or crème fraiche and vanilla.
Spread 2/3 of the cream on the base, then spread half of the lemon curd on top. Use a wooden stick to mix the two masses in a spiral on the surface and repeat the process with two more layers.
Bake the cheesecake in the oven for about 45 minutes.
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