Does anyone know a recipe for a sponge cake that I could use to make a huge cake for an engagement party?

Madeira cake

Ingredients:
4 oz/ 100g Marg or butter
4 oz/ 100g Castor sugar
2 large eggs
6 oz/ 175g S.R.flour

Method:
Grease a deep 8 inch cake tin and line the base with greaseproof paper. To give a better result, place the eggs (in there shells) in a cup of warm water at room temp for 5 minutes.
Cream the fat and sugar until very light. Add 1 of the eggs and a t.spoon of flour and beat well. Add the second and another t.spoon of flour and continue beating. Sift in the rest of the flour, and fold in lightly. Smooth into the prepared tin and bake in a moderate oven gas mark 4, 350 degrees F or 180 degrees C for 35 minutes. When cooked, turn out and cool on a wire rack. Store in a tin until needed.

Emma Nelson the founder of emmathechef :)

Here in Belgium there is a standard cake recipe for what is called (translation) 4 quarter cake. You weigh your eggs and then add the same weight in SR flour (plus 1/2 tsp of baking powder and 1 tsp of apricot jam or marmalade per 250g of flour ; the pectin in jam/marmalade gives a moister cake as it retains the moisture content thus improving the keeping quality),  the same weight of sugar, the same weight of soft butter or margerine and flavour with vanilla extract.  
Whisk as little as possible to get a smooth mixture and bake at 175C until golden brown and cooked through (skewer test if you have made a vast cake!). Cool and decorate as you wish, you can also vary this recipe by adding either cocoa/ dried fruit/ rhubarb/ apple/pineapple/chocolate pieces, nuts , just go creative!