In a bowl, whisk the butter until soft (or use a food processor), then add the sugar, and mix well again.
Add the eggs to the mixture, and mix well again.
Add the flour and mix until you have a homogenous dough.
Butter a baking form, then pour the dough into the form. The form should not be filled to more than half, as the dough will rise.
Bake off for 55 minutes, or until the cake is golden brown and ready. Use a wooden or metal skewer to prick into the cake - if it comes out without rests of dough on it, the cake should be ready.
Remove from the oven and leave to cool a bit before serving.