Roti Canai (Malaysian Flaky Butter-Layered Flatbread)

Mix 350 g all-purpose flour with 1 tsp salt and 1 tsp sugar. Add 1 egg and 180 ml milk and gather the mixture until no dry flour remains. Knead for about 8 minutes, stopping when the dough is smooth and elastic. If it feels sticky, let it rest briefly instead of adding enough extra flour to make it stiff. Coat the surface with part of the measured 3 tbsp oil, cover it, and rest it for at least 30 minutes. Divide the relaxed dough into 4 pieces and apply the remaining oil lightly to the work surface and your hands. Press and pull each piece outward from the center until the surface beneath it is almost visible. Divide 20 g melted butter across the four thin sheets, brushing each one lightly. Fold all four sides inward to form square parcels. Preheat a pan well over medium-high heat, apply a small amount of oil, and cook each side for about 2 minutes. Remove the flatbread when both sides are evenly golden and puffed in spots. While it is still hot, clap it gently from the edges to loosen the folded layers before they set together.