Pulse almonds or walnuts in a food processor until finely chopped.
- Add oats, cocoa powder, maple syrup, melted coconut oil, and salt; pulse until mixture sticks together when pressed.
- Press crust mixture firmly into the bottom and up the sides of a 9-inch tart pan. Refrigerate while preparing filling.
- Scoop solidified coconut cream from chilled coconut milk into a saucepan, reserving liquid.
- Add dark chocolate chips and maple syrup to the saucepan. Heat gently over low heat, stirring until smooth and melted.
- Remove from heat and stir in vanilla extract.
- Pour chocolate filling into prepared crust and smooth the top.
- Refrigerate tart for at least 4 hours or until set.
- Garnish with fresh berries, shaved chocolate, or toasted nuts if desired before serving.