Dark Chocolate Orange Cake

Cooking spray
3/4c powdered sugar
3 lg eggs
2 tbsp cornstarch
3 tbsp unsweetened cocoa
3 tbsp fresh orange juice
1 tbsp Triple Sec (orange-flavored liqueur)(OU)
1 tbsp hot water
Dash salt
2 oz bittersweet chocolate, chopped
Powdered sugar (optional)
Orange rind strips (optional)

Preheat oven to 350°. Coat an 8-inch spring form pan with cooking spray, then line bottom of the pan with parchment or wax paper. Wrap outside of pan with aluminum foil. Place 3/4 cup of sugar and eggs in a bowl, and beat with a mixer at high speed 7 minutes. Combine cornstarch and cocoa in a small bowl, set aside. Place juice, liqueur, water, salt, and chocolate in a small glass bowl, then microwave at high for 1 minute or until almost melted, stirring every 20 seconds until smooth. Add cornstarch mixture, and whisk until smooth. Gently stir one-fourth of egg mixture into chocolate mixture. Fold into remaining egg mixture. Scrape batter into prepared pan. Place pan in a 13 x 9-inch baking pan, and add hot water to larger pan to a depth of 1 inch. Bake at 350º for 20 minutes or until top is set. Remove cake pan from water, and cool 5 minutes on a wire rack. Loosen cake from sides of pan using a narrow metal spatula, then cool to room temperature. Cover and chill at least 4 hours or overnight. Garnish with powdered sugar and rind just before serving, if desired.