First, preheat the oven to 350ºF and line a muffin tin with muffin liners. Generously spray with nonstick cooking spray.

Next, prepare graham cracker crust. Place graham crackers and butter into a high-speed food processor. Process on high until the mixture forms a crumble.

Spoon 2 heaping tablespoons of the graham cracker crumble into each muffin cup. You should have enough crust to make 12 mini cheesecakes. Use a spoon to press the crumble down into the pan.

Bake graham cracker crust for 10 minutes at 350ºF. Remove the crust from the oven and let them cool completely. 

While the crust is baking, prepare the pistachio filling. Place softened cream cheese into a large bowl of a standing mixer (you can also use a handheld mixer) and mix on high until the cream cheese is whipped and soft. You may need to scrape the sides of the bowl a few times during this process. 

Turn the mixer to low and slowly pour the milk into the mixer until the milk and cream cheese are combined. 

Add the pistachio Jell-O packet to the bowl and mix on low until combined and the mixture begins to thicken. 

Scrape the sides of the mixing bowl and use a spatula to make sure all ingredients are combined together. Sometimes the pistachio pudding will stick to the bottom of the mixing bowl. 

Finally, scoop two heaping tablespoons of the pistachio mixture into each graham cracker cup and spread it out with the bottom of a spoon  (sometimes it helps to wet the spoon when you’re trying to spread the pistachio mixture out evenly) . Repeat until all cups are full. 

Place the cups into the refrigerator to set for at least 1 hour (sometimes the longer the better). 

Remove from the refrigerator and top each pistachio cup with a dollop of whipped cream and sprinkle the whipped cream with chopped pistachios.