Line a 10-in springform pan with parchment paper. Pulse the Speculoos cookies in a food processor, then add the spices and the butter (which should be very soft, almost melted). Press the resulting mixture firmly into the bottom of the pan to form the base. Set aside in the fridge.
Grate the zest from the half lemon, then squeeze the juice from the same. Separate the egg whites from the yolks. Blend the cream cheese, mascarpone, and lemon juice in a food processor, then incorporate the egg yolks one by one, followed by the sugar and the lemon zest.
Preheat the oven to 140°C (285°F). In a separate bowl, beat the egg whites until stiff peaks form. Gently fold the cream cheese mixture into the beaten egg whites using a spoon, mixing as gently as possible.
Bake for approximately 60 minutes; the cheesecake should feel firm to the touch yet still remain slightly soft in the center. Allow to chill in the refrigerator for 90 minutes before unmolding.
Serve cold.
If you don’t have speculoos on hand, you can use the regular graham crackers with an extra helping of spices (cinnamon, ginger, nutmeg) and use toasted sugar instead of regular sugar.