How to Make It
Preheat the oven to 350°. Butter and flour a 10-inch round cake pan.
Into a medium bowl, sift together the 1 3/4 cups of flour, baking powder and salt. In another medium bowl, whisk the melted butter with the olive oil and milk.
In a large bowl, using a handheld mixer, beat the eggs with the sugar and citrus zest until pale and thickened, about 3 minutes. Alternately beat in the dry and wet ingredients, starting and ending with the dry ingredients. Pour the batter into the prepared pan. Bake for about 30 minutes, until the cake is golden brown and the side pulls away from the pan. Transfer the cake to a rack and let cool before serving.