Lemon curd and blueberry cake

Ingredients

• spray oil
• 175 grams butter
• 1 cup caster sugar
• 1/2 teaspoon vanilla essence
• 3 eggs
• 2 cups self-raising gluten-free flour, sifted
• 1/2 cup lite sour cream
• 2 teaspoons lemon zest
• 1 tablespoon lemon juice
• 3 tablespoons lemon curd
• 1 cup blueberries, fresh or frozen
• cream or yoghurt to serve (optional)
• Icing (optional)
• 1 cup gluten-free icing sugar
• finely grated zest of 1 lemon
• 2 tablespoons lemon juice
• 1-2 tbsp water