Place cream, sugar, and zest in the bowl of an electric mixture and beat on high until stiff peaks form.
To assemble:
Place a single layer of shortbread cookies at the bottom of a parchment lined pan; if necessary, break cookies to fill the gaps.
Next, spread an even layer of the whipped cream, then the lemon curd over the cookies. Top with more cookies and repeat as necessary for desired number of layers.
Cover the top with plastic and chill, overnight, in the fridge.
When ready, remove the cake from the fridge and garnish with blueberries, pistachios, and a touch more lemon zest, if desired.