Remove top oven rack; move other to lowest position. Heat over to 325F. In medium mixing bowl combine coca and water; stir in 3 tbs sugar and 2 tbs vegetable oil; set aside. In second mixing bowl combine flour, 1-1/2 cups sugar, baking powder and salt. Add in order; water, vegetable oil and egg yolks; beat with spoon until smooth. In large mixer bowl beat egg whites with cream of tartar until very stiff peaks form; gently pour egg yolk mixture over beaten egg whites, folding just until blended.
Measure about 2 cups batter; add to chocolate mixture. Gently fold until well blended. To remaining batter carefully blend in grated orange peel. Spoon half the orange batter in an ungreased inch tube pan; dollop with halt the chocolate batter. Repeat layers of orange and chocolate batters. With narrow spatula, swirl gently through batters to marble, leaving definite orange and chocolate areas. Bake 1 hour and 15 to 20 minutes or until top springs back when touched lightly. Remove from oven and immediately invert pan until cool. Remove cake from pan; invert onto serving plate. Spread top of cake with Orange Glaze, allowing some to drizzle down sides.
Makes 12 to 16 servings.
In medium saucepan over low heat melt 1/3 cup butter or margarine. Remove from heat. Stir in 2 cups confectioners sugar, 1/2 tsp grated orange peel and 2 to 3 tbs orange juice or until desired consistency.
Makes about 1-1/2 cups glaze.
Cajun Country -- New Iberia, Louisiana