Preheat and Prep: Begin by preheating your oven to 180°C (350°F, gas mark 4). Grease a 1.5-liter baking dish with butter.
Mix Butter and Sugar: In a large bowl, cream together the softened butter and sugar until pale and fluffy. Incorporate the lemon zest into the mixture.
Egg Yolks: One at a time, beat in the egg yolks, ensuring each is fully incorporated before adding the next.
Flour and Milk: Sift the flour into the mixture, alternating with milk, and stir gently to combine. Add the lemon juice, mixing well to ensure a smooth consistency.
Whisk Egg Whites: In a separate, clean bowl, whisk the egg whites until they form stiff peaks. Carefully fold these into the lemon mixture to keep the air in.
Bake: Pour the mixture into the prepared baking dish. Place the dish in a roasting pan and fill the pan with boiling water to come halfway up the sides of the dish. Bake for 35-40 minutes until the top is golden and the sponge feels firm to the touch.
Serve Warm: Let the pudding cool for a few minutes before serving. It’s best enjoyed warm, allowing the contrasting textures and temperatures to shine.
