Preheat your oven to 350°F (175°C) and grease a 9-inch pie dish with butter or cooking spray.
In a mixing bowl, whisk together the sugar, milk, melted butter, flour, baking powder, and salt until smooth.
Add in the eggs, lemon zest, and fresh lemon juice. Whisk until fully combined and the mixture is light and airy.
Pour the batter into the prepared pie dish. Do not worry if it seems runny; it will form its own crust during baking.
Bake in the preheated oven for 60 minutes or until the top is lightly golden and a toothpick inserted in the center comes out clean.
Once done, remove from the oven and let it cool for about 15 minutes. The pie will deflate slightly as it cools.
Serve warm or cold, dusted with powdered sugar if desired.