Ingredients
2 cups all-purpose flour
4 teaspoons baking powder
1/2 teaspoon salt
1 1/2 cups sugar, divided
1/2 cup neutral-tasting oil, such as safflower
6 large eggs, separated
2 tablespoons finely grated orange zest and 1/2 cup fresh orange juice (from 2 to 3 navel or Valencia oranges)
1/4 cup cold water
1/4 teaspoon cream of tartar
Whipped cream, for serving
Candied Orange Zest, for serving (optional)
Preparation
Preheat oven to 325 degrees. In a large bowl, whisk together flour, baking powder, salt, and 1 cup sugar. Make a well in center of flour mixture. Add oil, egg yolks, orange zest and juice, and 1/4 cup cold water; whisk batter until smooth.
With an electric mixer on medium-high speed, whisk egg whites and cream of tartar until soft peaks form. Gradually add the remaining 1/2 cup sugar, 1 tablespoon at a time; continue to beat until stiff peaks form. Using a flexible spatula, gently fold half of egg-white mixture into batter. Fold in remaining egg-white mixture just until combined (do not overmix).
Pour batter into a 10-inch footed angel food cake pan with a removable bottom; bake until a cake tester inserted near center of cake comes out clean, 55 to 60 minutes. Remove from oven; invert, still in pan, onto a baking sheet. Let cool completely. Run a sharp knife around edges to release cake. Serve topped with whipped cream and candied zest, if desired.
