Thoroughly grease a 10 to 12 cup microwave safe Bundt pan with shortening; sprinkle with 1/2 cup of the chopped walnuts to coat evenly.

Sift flours, baking powder and baking soda; set aside. Cream butter and sugar until fluffy; beat in eggs, one at a time. Stir sour cream or yogurt, banana and liqueur into egg mixture. Combine flour mixture with banana-egg mixture; stir in remaining walnuts. Spoon into prepared pan. Place on top of a microwave-proof bowl in center of microwave. Cook on medium for 10 minutes, then on high 5 to 7 minutes until cake tests done, turning twice. Let cake stand 15 minues. Turn out onto serving place. Let cool.

Mix sifted confectioners' sugar and orange juice until smooth. Pour glaze evenly over cake and serve.