Preheat oven to 350 degrees F (176 C).
Spray an 8” fluted tart shell. In a food processor, pulse together graham cracker crumbs and pistachios until pistachios are mostly broken up into small chunks. Add melted butter and pulse a few more times.
Spread pistachio-graham cracker base onto tart pan and work your way up the sides, distributing an even amount all over the pan. Bake for 14 minutes, or until edges appear crispy. You may need to flatten out the tart shell again with the back of measuring up if the shell appears to have puffed up.
When the tart shell is baked, you may turn off the oven and prepare the Greek yogurt filling. The tart shell must be cooled completely before filling.
To prepare the filling, sprinkle powdered gelatin over the cold water and let it bloom. In a small saucepan, heat up milk and sugar on medium high heat. Be careful to not boil.
In a separate bowl, combine Greek yogurt, lemon juice and zest.
Once milk is hot and sugar has dissolved, add bloomed gelatin to the pot and stir around until all the gelatin dissolves. Next, pour the milk mixture over the Greek yogurt and whisk to combine.
Pour mixture into the cooled tart shell and place in the fridge. You may want to put the tart pan over another cookie sheet in the fridge just in case the mixture seeps thru some microscopic holes… trust me I’ve been there, and cleaned that mess before.
Chill for 2+ hours.Decorate with slices of strawberries, golden raspberries, or whatever else you’d like! Enjoy!