PREHEAT oven to 350°. Brush a 9-inch springform pan with olive oil. Line bottom of pan with parchment paper, and brush parchment with olive oil.
FOR CAKE: In a large bowl, beat egg yolks and ½ cup sugar with a mixer at medium speed until combined. Add oil and orange zest and juice, beating until combined, about 2 minutes. Sift Swans Down® Cake Flour over egg yolk mixture, and whisk to combine. Add pistachios, stirring well.
IN another large bowl with clean beaters, beat egg whites with a mixer at high speed until tripled in volume. Gradually add remaining ¼ cup sugar, beating until soft peaks form. Gently fold one-third of egg whites into yolk mixture. Fold in remaining egg whites. Pour batter into prepared pan.
BAKE until a wooden pick inserted in center comes out clean, 40 to 45 minutes. Let cool in pan for 10 minutes. Run a knife around edges of pan to loosen cake. Remove cake from pan, and carefully peel off parchment paper.
FOR GLAZE: In a small bowl, whisk together confectioners’ sugar and orange zest and juice. Pour over cake.
Makes 1 (9-inch) cake