Adjust rack to middle position and preheat oven to 350°F.

Prepare a 9 or 10 inch tart pan with a removable base. Cut out parchment paper to fit the bottom of the pan and place it inside. I like to spray the bottom with cooking spray and place the parchment on top so it sticks.

Place all ingredients for the crust into the bowl of a food processor. Run until uniformly combined and sticky, scraping the sides and bottom if necessary. You will still see oat flecks in the mixture.

Press mixture evenly into the tart pan on the bottom and up the sides.

Bake for 18-20 min, until lightly golden. Let cool completely before adding any filling.

Spread the pistachio paste evenly onto the bottom of the tart. Place into the refrigerator while the chocolate filling is made.

In a medium-sized saucepan, combine the coconut milk and coconut oil and set over medium-high heat, whisking to combine evenly. Bring to a simmer, then turn off the heat and add the dark chocolate, cocoa powder, agave, and vanilla bean paste. Let sit for 2 minutes, undisturbed, then whisk to combine until smooth. Season with sea salt, to taste (I like it decently salty).

Pour into the tart shell on top of the pistachio paste. Pour anything leftover into ramekins or small bowls and eat with whipped cream, if desired.