Gluten free birthday sponge cake

Sponge

• butter, for greasing
• 220 g raw sugar
• 6 eggs, room temperature
• 2 tsp natural vanilla extract
• ½ tsp bicarbonate of soda
• 1 ½ tsp cream of tartar
• 130 g gluten free cornflour

Cream cheese frosting

• 250 g cream cheese, softened
• 100 g unsalted butter, cut into pieces, softened
• 200 g pure icing sugar
• 1 tsp natural vanilla extract
• 1 tbsp lemon juice