In a blender, crush the cookies into crumbs. Melt the butter in the microwave then mix with the mixed biscuits.
Pack the mixed biscuits in the bottom of a 20cm springform pan (I add a rhodoïd film first to facilitate the unmolding of the cheesecake). Press well with the back of a spoon or a glass. Refrigerate while waiting for the rest.
Cheesecake filling
Soften the gelatin in cold water.
In a very small saucepan, heat 2 tablespoons of lemon juice and melt the well-drained gelatin in it off the heat.
In a bowl or in a food processor, whisk the Philadelphia, mascarpone, sugar, lemon zest and remaining lemon juice until stiff.
Pour in the lukewarm juice/gelatin mixture and whisk again to obtain a smooth mixture.
Separately, whip the liquid cream until stiff.
Fold the whipped cream into the cream cheese mixture using a spatula and whisk until smooth. This filling should already be firm.
Place this filling in the mold, on top of the layer of pressed biscuits. Smooth the top with a small spatula. Refrigerate overnight.
lemon curd
Pour the lemon juice into a saucepan and heat over low heat.
Separately, whisk the eggs and sugar until the mixture lightens in color.
In a small bowl, pour the cornstarch and mix with a little hot lemon juice (this prevents lumps).
Pour the dissolved cornstarch onto the egg mixture while whisking, also adding the remaining hot lemon juice.
Return everything to the saucepan and heat over low heat, whisking constantly for about 4 minutes. The mixture should thicken visibly. Keep whisking to prevent sticking.
Once you have a smooth texture, turn off the heat and add the butter in pieces. Whisk one last time to smooth it out.
Pour into a clean, dry jar and let cool before refrigerating.
Assembly
Once the cheesecake is ready, spread the lemon curd on top using a spatula or tablespoon.
Add the decoration of your choice: whipped cream domes, zest, lemon pieces, etc.
Notes
I recommend serving this cheesecake straight from the refrigerator when it's chilled. You can keep it refrigerated until ready to serve.Well protected, under a bell or in an airtight container, it can be kept up to 4-5 days in the refrigerator.