Chocolate Cake with Chocolate-Orange Frosting

Cake:

• Nonstick vegetable oil spray
• 1 cup all purpose flour
• 1 cup sugar
• 1/2 cup whole wheat pastry flour*
• 6 tablespoons unsweetened cocoa powder
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 3/4 cup water
• 1/3 cup vegetable oil
• 1/4 cup frozen orange juice concentrate, thawed
• 1 teaspoon vanilla extract
• 1 teaspoon distilled white vinegar

Frosting:

• 8 ounces bittersweet chocolate (donot exceed 61% cacao), chopped
• 6 tablespoons (3/4 stick) vegan “butter” (such as Earth Balance) or margarine, room temperature
• 1 cup powdered sugar
• 3 tablespoons frozen orange juice concentrate, thawed, divided
• 1/2 teaspoon vanilla extract
• Large pinch of salt
• 1/4 cup light agave nectar**