A good sponge flan base is to use the light genoise recipe.
It has the light sponge texture but not dry
a typical example is this :

Use
2 parts of eggs( content only) + 1 part caster sugar + 1 part self
rising flour + 1/3 part of melted butter ( all measured by weight).

Calculate the total batter weight required as based on your total
recipe and from there you can use the given ratios to arrive .
This recipe is lighter (if made properly)than the one you made so you
can try this ratio
100 grams eggs( about 4 oz)
50 grams sugar( about two oz)
50 grams Self rising flour ( about two oz)
15-20 grams melted butter( 1/2-2/3 oz))

Prepare this by beating the eggs with the sugar until thick and light
or until the whip marks are retained when pulled out from the egg foam.
Or if you dip a spatula you can form a figure 8 with the dripping egg
foam.
Sift the flour on top and fold carefully, follow with melted butter
until evenly blended.
Do not overmix.
Pour into the prepared into prepared flan tin and bake at 380 degree
until the cake is golden brown and spongy to touch.

Note: you can add vanilla sugar in this recipe if you like a packet is
enough for the given recipe.

da wrote:
> Apologies if this comes through twice. My original post doesn't seem
> to be showing up -- at least I'm not able to view it.
> --Vic
>
> I'm trying to make a sponge-based flan. The recipe I have is as
> follows:
>
> 1 egg
> 3 tablespoons warm water
> 2 1/2 ounces (75g) sugar
> 3 1/2 ounces (100g) flour
> 1 packet of vanilla suga
> 1 teaspoon baking powder.
>
> The instructions are pretty basic:
> Whisk egg and water until frothy
> Gradually add sugar and vanilla sugar
> Whish until thick and creamy
> Mix together flour and baking powder and seive onto whisked mixture
> Fold gently together
>
> This all goes into a moderately hot (340 degrees Fahrenheit to 390
> degrees Fahrenheit) for 20 to 25 minutes.
>
> Before the cake even came out of the pan, I could tell it wasn't
> right. It was much too heavy.
>
> The texture looks good for a sponge -- lots of small air pockets. It
> came out of the pan perfectly fluted edges and all.
>
> The taste is a bit flat: a bit too dry and a bit too hard. Almost like
> day old baking.
>
> The recipe comes from a book I usually have good luck using.
>
> Are the proportions wrong? Is there too much flour? Is the entire
> recipe off? Was my technique faulty? Or was it just a fluke and I
> should try again.
> --Vic