Beat the butter until fluffy, then progressively add the sugar and the eggs one at a time.
Now you can add the flour, the baking powder the zest as well as the juice from the two oranges.
Butter a middle-sized springform. I really recommend to take a springform, this is the only way you can get the cake out without breaking it as it is really soft.
Pour the cake batter into the cake mold and bake for 30 minutes.
Check with a skewer if the cake is done. The cake is done when the skewer comes out clean.