Lemon and Poppy Seed Battenberg Cake

Name: Lemon and Poppy Seed Battenberg Cake
Prep time: 30 min
Cook time: 1 h 45 min
Total time: 1 h 45 min
Yield: 8 slices
Ingredients: 1 lemon; 75 g granulated sugar; 50 g unsalted butter; 2 egg yolks; 1 lemon; 175 g caster sugar; 175 g unsalted butter; 175 g self-raising flour; 3 large eggs; 1 tsp baking powder; 1 pinch fine sea salt; pink food colouring gel; 1 tsp lemon juice; 2 Tbsp poppy seeds; 320 g marzipan; 50 g icing sugar; 1 - 2 tsp lemon juice; edible cake decorations