Why a Russian Rhubarb Cake Turned Out Flat and Oily

I took this recipe from the Irish examiner and carefully transposed the recipe to US measurements: 1/4 c sugar, little less than 1/2 c flour and 1 cup plus 3 tablespoons butter and it was flat and very oily. I beat the eggs vigorously as they were the only leavening ingredient but am not sure what I did wrong. I love the idea of a simple, light and not too large sponge and can't find anything comparable online to this recipe.

1. Preheat the oven to 200°C.

1. Melt the butter without getting it very hot. Then mix all the ingredients except the rhubarb and beat vigorously.

1. Spread the mixture over a well-greased Swiss roll tin and cover with the diced rhubarb.

1. Sprinkle generously with sugar and bake for 45 minutes, lowering the heat slightly if cake looks like getting too brown. Cut into slices and remove them carefully with a spatula to cool on a cake-rack.

Ingredients

- 4 eggs

- 270g butter

- 50g sugar

- 50g flour

- 1 dessertspoon lemon juice

- ½ tsp cinnamon

- 400g rhubarb, diced

- pinch of grated nutmeg