Dark Chocolate and Orange Tart with Toasted Almonds

Name: Dark Chocolate and Orange Tart with Toasted Almonds
Ingredients: 1 orange; 1/4 cup sugar; 2 tablespoons water; 1/2 cup (1 stick) unsalted butter, room temperature; 1/2 cup sugar; 1/4 teaspoon ground cinnamon; 1/4 teaspoon salt; 6 tablespoons unsweetened cocoa powder; 3/4 cup all purpose flour; 1 cup slivered almonds, toasted, coarsely chopped; 2 teaspoons sugar; 1 teaspoon ground cinnamon; 1 cup heavy whipping cream; 8 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped; 1 tablespoon Grand Marnier or other orange liqueur