Sift the plain flour, caster sugar and a pinch of salt into a large bowl to remove any lumps.
Make a well in the centre of the dry ingredients, crack in the eggs and whisk gently until smooth.
Gradually whisk in the milk until you have a smooth, lump-free batter.
Whisk in the melted unsalted butter until fully incorporated.
Cover the bowl with cling film and chill the batter in the fridge for at least 30 minutes, ideally up to an hour.
Heat a 20–24 cm non-stick frying pan over a medium heat and lightly grease with butter or oil.
Pour about 60–80 ml of batter into the centre of the pan, tilting and swirling it to coat the base in a thin layer.
Cook for 1–2 minutes until the edges start to turn golden. Loosen the crepe with a spatula and carefully flip it over.
Cook the other side for 30–60 seconds until lightly golden, then transfer to a plate and repeat with the remaining batter.
Stack the crepes on a plate and serve warm with your favourite fillings or toppings.