For crust, preheat oven to 350 F. On large rimmed baking sheet, place 8 to 10 inch tart tin with removable bottom. In food processor or blender, blend oats, almonds, sugar, cinnamon, and salt until coarse meal forms. Pulse in coconut oil until it is fully combined and a loose dough is formed. Firmly press dough into tart tin, including up the sides. Bake for 15 minutes. Cool completely. Refrigerate until ready to assemble.

For pudding, in medium saucepan over medium heat, whisk nondairy milk, pumpkin, chocolate, arrowroot or tapioca flour, sugar, cinnamon, and salt. Whisk constantly until chocolate is melted, about 5 minutes. Continue to whisk for 8 to 10 minutes, until mixture begins to thicken and large bubbles start to pop on top. Once thick and bubbling, continue to whisk for 1 to 2 minutes longer. Strain through fine sieve into large bowl. Stir in vanilla. Cover and cool to room temperature (do not refrigerate until poured into the crust).

To assemble, whisk cooled pudding mixture until smooth and pour into prepared, cooled crust. Smooth out top and refrigerate for at least 5 hours or up to 1 day. Garnish with pomegranate seeds, cranberries, or almonds (if using); slice and serve chilled.