Pre-heat oven to 180°C / 160°C fan assisted oven / gas mark 5.
Grease and line an 8 inch x 4 inch round cake tin.
Chop the cherries roughly, so some are halved and some quartered.
Toss the cherries with the extra tablespoon of tapioca flour until all the cherries are well coated then set aside.
Whisk together the flours, almonds, baking powder and salt in a large mixing bowl and set aside.
Beat together the butter and sugar, using a stand mixer or electric beater, until light and creamy.
Add the eggs one at a time, beating well after every addition.
Pour in half the flour and mix in well, scraping down the sides. Mix in the zest and juice of the lemon then add the other half of the flour.
Rest your cake batter for 20 minutes at this point to help the gluten-free flours absorb the liquid ingredients.
Stir in the cherries until evenly dispersed then pour into the cake tin.
Bake for about 70 minutes or until an inserted cocktail skewer comes out clean.
Leave to cool in the tin for 10 minutes then turn out carefully. Leave to cool fully on a wire rack then sprinkle the three teaspoons of sugar over the top of the cake.