This is a simple cake that feeds a large group. It needs to stay in the pan to soak up the orange syrup as it cools, so it is best portioned and plated in the kitchen.
Preheat the oven to 350°F (175°C) and grease a 9- × 13-inch (23×33 cm) cake pan.
Beat the butter, ¾ cup (185 mL) of the sugar, and the orange zest until fluffy, then add the egg yolks and beat them in. Beat in the vanilla. In a separate bowl, sift the