• Add the mascarpone cheese, sugar, salt and vanilla to a bowl. Whisk on low speed for just ~1-2 minutes until the mixture looks creamy (it's ok it the sugar doesn't feel fully dissolved yet) - don't overmix. Scrape the bowl
• Add the pistachio cream and whisk for just a few seconds until combined. Don't overmix and scrape the bowl again
• Separately, whisk the heavy cream until it thickens up and starts to form ripples (soft peak stage). Don't whip to stiff peaks!
• Add the heavy cream to the rest of the mixture in 2 additions, and use a rubber spatula to very slowly and gently fold it in. 
• You should have a fluffy and light pistachio mascarpone cream. If it looks slightly grainy, add 2-4 tbsp heavy cream (liquid, not whipped) and gently fold it in
• To assemble, first add a layer of ladyfingers in your serving pan (I use a 9x9" square pan). Dip the ladyfingers in the coffee for just ~2 seconds each and arrange them tightly in the bottom of the pan
• Add half of the pistachio mascarpone cream and spread it out evenly
• Repeat with another layer of ladyfingers soaked in coffee
• Spread on the remaining pistachio mascarpone cream. If you'd like, you can also pipe it on with any piping tip of choice to give the tiramisu a finished look
• Cover with cling wrap and refrigerate for 6 hours or overnight
• Dust with cocoa powder before serving. Slice, serve and enjoy!

Video tutorial: