Preheat your oven to 350°F (175°C). In a mixing bowl, combine finely chopped pistachios, crumbled feta cheese, grated Parmesan, breadcrumbs, and melted butter. Use a fork to mix until they resemble wet sand. Set aside.

Press the pistachio mixture evenly into the bottom of a greased springform pan and bake for about 10 minutes until golden brown and firm. Allow to cool.

In a skillet, heat olive oil over medium heat. Add chopped mushrooms and minced garlic, sauté until tender, then cool slightly before adding to filling.

In a mixing bowl, beat softened cream cheese until smooth. Gradually add sour cream, eggs, and Parmesan, mix well. Fold in the mushroom mixture, season with salt and pepper.

Pour filling over the cooled crust and bake for 35 to 40 minutes until the center is slightly wobbly. Remove and cool for 10 minutes before releasing from pan.

Garnish with fresh thyme and additional chopped pistachios before slicing. Serve and enjoy!