Preheat the oven to 160°C (32°F).
Beat the butter and sugar together with an electric whisk, until they form a light, creamy consistency.
Beat in the egg, and then beat in the lemon curd.
Sift in the polenta, ground rice, ground almonds, xanthan gum and baking powder, then add the poppy seeds and lemon zest, and fold the mixture until combined.
Add and stir in the lemon juice, then pour into a lined loaf tin and bake in the oven for 40-45 minutes.
Remove from the oven when the cake is golden brown, beginning to peel away from the lining, and a knife stuck into the middle comes out clean.
Allow the cake to cool a little whilst you make the drizzle: Add all the ingredients (lemon juice and zest, sugar, and gin) into a small saucepan.
Simmer the drizzle over a high heat for 2-3 minutes, until it forms a syrup.
Leave the cake in the tin and poke 10-12 small holes in the top with a skewer. Drizzle with the lemony syrup and allow to cool completely before turning out.