Preheat the oven to 180 C / Gas 4. Grease a round 22cm springform cake tin.
For the base:
Place biscuits in a sealed bag and crush with a rolling pin, then transfer to a mixing bowl. Add finely chopped walnuts and melted butter and mix well until combined. Spoon the biscuit mixture into the prepared springform cake tin and press down with the back of a spoon to compact.
Bake in the preheated oven for 5 minutes. Remove from the oven and set aside.
For the filling:
Whisk double cream until soft peaks form and set aside. In a mixing bowl, combine cream cheese with sugar and mix well. Add dulce de leche and eggs, one at a time. Try not to beat too energetically as you want to avoid adding too much air into the mixture which may lead to cracking on the surface of the cheesecake. Add whipped cream and gently mix well, until well combined. Spoon the mixture into the prepared tin over the biscuit base.
Bake in preheated oven for 1 hour and 15 minutes. Do not open door while baking. Once it is done, let it cool off completely at room temperature for 30 minutes, and then chill in the fridge for at least 3 hours (or preferably overnight) to achieve an optimum texture.
Just prior to serving, decorate with walnuts and dulce de leche (in little dollops or peaks). Slice and serve.