Preheat the oven to 325°F and wrap the outside of a 9-inch springform pan with two layers of foil. In a bowl, stir together the almond flour, sugar, melted butter, and salt until evenly combined and slightly crumbly.
Press the mixture firmly into the bottom of the pan using the flat bottom of a measuring cup. Bake for 12 to 14 minutes until lightly golden around the edges, then set aside to cool.
In a large bowl, beat the cream cheese and sugar on medium speed until very smooth and creamy, about 4 minutes. Add the pistachio butter and beat until fully incorporated with no streaks remaining. Scrape down the bowl.
Add the cornstarch, vanilla extract, and almond extract, mixing on low until combined. If using food coloring for a more vibrant green, add it now and mix briefly.
Add the eggs one at a time, mixing on low speed after each just until the yolk disappears. Fold in the sour cream by hand with a spatula until the batter is smooth.
Pour the filling over the cooled crust and smooth the top. Set the pan in a roasting pan and add hot water until it reaches halfway up the sides. Bake for 55 to 65 minutes, until the outer ring of the cheesecake is set and the center has a gentle jiggle.
Turn off the oven, crack the door open, and let the cheesecake rest inside for 1 hour. Remove it from the water bath, peel off the foil, and refrigerate for at least 6 hours or overnight.
Whip the heavy cream and powdered sugar together until stiff peaks form. Spread or dollop over the chilled cheesecake, then scatter the chopped pistachios generously on top. For extra color and contrast, sprinkle with crushed freeze-dried raspberries before serving.