7 ounces vegan dark chocolate, melted & slightly cooled
2/3 cup agave syrup
2 teaspoons vanilla extract
2/3 cup plus 1 teaspoon coconut oil, melted & slightly cooled
1/4 teaspoon kosher salt
2 tablespoons old-fashioned oats
1 tablespoon demerara sugar
Preheat the oven to 350 degrees F. For the curst, pulse the oats, flour, coconut oil, agave syrup, cocoa powder, salt and cinnamon until the mixture resembles wet sand. Press into the bottom and up the sides of a rectangular tart pan with a removable bottom. Bake the crust for 20-25 minutes until golden brown and toasty. Transfer to a wire rack to cool completely.
For the filling, dissolve the espresso powder in 3/4 cup very hot water in the bowl of a food processor. Stir in the cocoa powder and let sit for 5 minutes before adding the melted chocolate, agave syrup, vanilla extract, 2/3 cup coconut oil and salt. Process until smooth and thick, about 30 seconds. Pour the filling into the tart shell. (You may have a little extra which can be used for truffles). Gentle tap the pan on the bottom to remove any air bubbles.
Toast the oats and remaining 1 teaspoon coconut oil in a small skillet over medium heat, stirring constantly, for 3 minutes. Stir in half the demerara sugar. Let it melt before removing from the heat and stirring in the remaining sugar. Cool the oat mixture and sprinkle over the tart. Chill the tart in the refrigerator until the filling is set, at least 1 hour. Slice the chilled tart with a hot dry knife. Let it sit at room temperature for 15-20 minutes before serving. Store covered in the refrigerator.