Vegan Chocolate Tart With Salted Oat Crust

Name: Vegan Chocolate Tart With Salted Oat Crust
Cuisine: European, Mediterranean, French
Ingredients: 1 1/4 cups old-fashioned oats; 3/4 cup whole wheat flour; 1/3 cup virgin coconut oil, melted, slightly cooled; 1/4 cup light agave syrup (nectar); 2 tablespoons unsweetened cocoa powder; 3/4 teaspoon kosher salt; 1/2 teaspoon ground cinnamon; 1/2 teaspoon instant espresso powder; 1 cup unsweetened cocoa powder; 7 ounces vegan dark chocolate, melted, slightly cooled; 2/3 cup light agave syrup (nectar); 2 teaspoons vanilla extract; 2/3 cup plus 1 teaspoon virgin coconut oil, melted, slightly cooled; 1/4 teaspoon kosher salt, plus more; 2 tablespoons old-fashioned oats; 1 tablespoon demerara sugar, divided; Flaky sea salt; A 9"-diameter or a 13 3/4x4 1/2" tart pan with removable bottom