Beat the cream cheese and sugar on medium low in a bowl until it is light and fluffy. Add the eggs and nuts and beat until well incorporated.
Pour the filling in to the springform pan.
With a stick blender or fork, stir the 3 Tbsps whipping cream in to the ⅓ cup pistachio cream until they are evenly mixed. It should be thick but pourable. See Note 2.
Starting at the center of the filling, drizzle the pistachio cream gently in smaller, then wider circles toward the outer edge. Stop a couple of inches from the outer edge of the pan. Take a toothpick or small knife tip and gently swirl the pisachio cream in to the cheesecake.
Set the springform pan into the waterbath pan. Bake 45-50 minutes until the edges turn golden and start to pull away from the edge. The center of the cheesecake will be a bit soft but should not be runny.
Remove the pan from the water bath and allow the the cheesecake to cool. Refrigerate at lease 4 hours. This can be made a day ahead and stored air tight in the fridge if you like.
When ready to serve, whip the 1 cup whipping cream to soft peaks. Add the ½ cup pistachio cream and mix gently until it is just incorporated. Do not overmix. If the mixture goes grainy, add more whipping cream a bit at a time until it smooths out again.
To serve, add a piece of cheesecake to serving plate, drizzle with the Pistachio Cream Garnish and sprinkle some crushed pistachios on top.
Cheesecake will keep well in the fridge for 3 days, tightly sealed. Cheesecake can be frozen up to 3 months. Defrost in the fridge the day before you plan to serve it.