Toasted Marshmallow and Rhubarb Cake | Nigella's Recipes | Nigella Lawson

Ingredients

• 500 grams forced rhubarb
• 100 grams caster sugar
• 6 large eggs (at room temperature)
• 1 unwaxed lemon
• 100 millilitres full fat milk (at room temperature)
• 25 grams cornflour
• 100 grams plain flour
• 2 teaspoons baking powder
• ½ teaspoon bicarbonate of soda
• ¼ teaspoon fine sea salt
• 150 grams caster sugar
• 150 millilitres vegetable oil (plus more for greasing)
• 6 egg whites from eggs above
• 350 grams caster sugar
• ½ teaspoon cream of tartar
• 2 teaspoons vanilla extract