Zingy lemon bars

Had a couple of lemons left in the fruit bowl so thought I'd make a cake. Didn't want to make my usual drizzle cake, so found this recipe in an old copy of a French magazine.

I did a very stupid thing and opened the oven to check that the cake hadn't overcooked - so of course it's now sunk in the middle! I still haven't got the measure of this gas cooker - several things I've cooked lately have been overcooked, hence the checking of the cake! That's my excuse anyway!

Bottom of cake
125g plain flour
pinch salt
35g icing sugar
100g unsalted butter
2 drops vanilla extract

Topping
2 medium eggs
170g caster sugar
grated zest and juice of a large lemon
1 tbspn plain flour
1/2 tspn bicarb. of soda
icing sugar to dust

Preheat oven 180C/gas4/350F
Grease a 20cm square cake tin.

Put flour, icing sugar and salt in a food processor and mix. Add the butter and vanilla extract and blitz till the mixture becomes a soft dough.
Press this evenly into the bottom of the cake tin and prick with a fork.
Bake for 12-15 mins till it's lightly golden and firmish.
Leave to cool in tin.

Whisk the eggs with a hand mixer till frothy and gradually whisk in the sugar till thick and foamy. Whisk in the lemon juice and zest then the flour and bicarb.
Pour this over the bottom and bake for 20-25 mins till golden brown.

Leave to cool in the tin and then cut into 12 pieces. Dust with icing sugar.

It has a good lemony tang and I like the crunchy base.