In food processor, pulse chocolate cookies into fine crumbs. Add finely chopped pistachios, melted coconut oil, maple syrup and cocoa powder. Pulse until mixture holds together when pressed.

Use back of spoon to press crust mixture firmly into bottom and sides of tart pan with removable bottom. Pack it tightly so it sets well. Refrigerate while preparing filling.

Use small saucepan to heat coconut milk over medium heat until it just begins to simmer. Remove from heat and add chocolate chips. Let sit 2 minutes, then whisk until smooth and glossy. Stir in vanilla. Let ganache cool for 15 minutes at room temperature, until it is slightly thickened but still pourable.

For pistachio butter layer, in high-power blender, blend roasted pistachios 3–6 minutes, scraping sides until smooth paste forms. Add 1 tablespoon neutral oil and continue blending. Add maple syrup. Add up to 1 more tablespoon of oil, if needed, to achieve creamy, spreadable consistency. Spread thin, even layer over chilled crust before adding ganache.

Pour ganache gently on top and smooth surface.

Sprinkle tart with chopped roasted pistachios.

Refrigerate for at least 4 hours. For firmer, yet still smooth texture, refrigerate 8 hours or overnight. Serve chilled.