Lemon Drizzle Cake - gluten free

I used to make lemon drizzle cake a lot for a cafe, but discovered I had never written it up so when I wanted to make on I had to do an Internet hunt.  I based this cake on the BBC Good Food recipe.  Making this cake marks a sad moment for me as it is the last day of my glass course at the excellent shop/training/studio at the Creative Glass Guild in Bristol.  My teacher, Jen, is fantastic, full of expertise and very kind to over-enthusiastic novices. I asked what type of cake to bring and she requested lemon drizzle, so her wishes trump the other students' please for ginger, parkin.....

Slight problem in that I have given away so much flour recently for people to test my bread recipe that I have run out of tapioca.  I thought I had a whole box left - lots of urid and lots of brown rice but no tapioca, and no store in Worcester sells it. I also ran out of baking powder and then forgot to get it when I went into town, so not the best start.  By using the tapioca I keep plain for thickening sauces or making tapioca gloop for flatbreads I managed to make 225g flour, which the recipe called for, but that seemed a bit stingy for thirteen hungry artisans.  Another 75g of almond flour makes this cake more substantial.  I forgot to increase the sugar and had no more butter, so this is a cake which is tangy and not very sweet.  However, my regular taster, who has a very sweet tooth, declared it to be perfect.

Ingredients:
225 g self raising flour (I use urid, 40%, tapioca 40% and rice 20%, with 1 tsp baking powder for 100g flour to make self raising four)
75g almond flour/meal
225 g butter, soft
225 g sugar for cake
5 eggs
Zest and juice of 2-3 lemons depending on how tangy you like your cake.  I used 2.5
100g sugar for topping

Set oven at 175C fan

Beat the butter until light and fluffy, add sugar and beat until fluffy.  Mix in eggs a little at a time, then add the lemon zest (not the juice) and flours, a little at a time, beating well between each addition.

Spoon the batter into a greased/lined baking tin.  I used a square tin as I wanted lots of shallow pieces to make them easier to eat without plates or cutlery.

Bake for 40-50 minutes until the top springs back when lightly pressed and a knife comes out clean.

Leave in tin to cool.  Mix the lemon juice with the remaining 100g of sugar.  Pierce the cake with a fork and slowly pour the lemony sugar over the cake.  Leave in tin to cool completely

The lemon sinks in and the sugar makes a fine crust on the surface.