Swedish Princess Cake

Name: Swedish Princess Cake
Prep time: 1 h
Cook time: 20 min
Total time: 1 h 20 min
Cuisine: European
Ingredients: 50g (3½ tbsp) butter; 4 eggs (medium); 150g (¾ cup) sugar; 75g (⅔ cup) cornstarch (see note 2); 70g (½ cup + 1 tbsp) spelt flour (see note 3); 1 tsp baking powder; 100ml (⅓ cup + 4 teasp) milk; 100ml (⅓ cup + 4 teasp) cream; 2 eggs (medium); 2 tbsp sugar; 1 tbsp cornstarch; 2 tsp vanilla extract; 750-1000ml (3-4 cups) whipping cream; jam (see note 4); marzipan cover (or make your own); decoration (see note 5); Icing sugar (for sprinkling)