Preheat your oven to 350°F (175°C) and melt ½ cup of unsalted butter in a 9×9-inch baking dish.

In a large mixing bowl, combine 1 cup of all-purpose flour, 1 tablespoon of baking powder, ¼ teaspoon of salt, and 1 cup of granulated sugar. Whisk well.

Add 1 cup of buttermilk, 1 teaspoon of vanilla extract, and optional 1 teaspoon of lemon extract to the dry mixture. Stir gently until smooth.

Pour the prepared batter over the melted butter in the baking dish without stirring.

Spoon 1 cup of lemon pie filling or lemon curd evenly over the top of the batter.

Bake for 45-55 minutes until puffed and golden brown, with the center slightly soft.

Cool for 10-15 minutes, then slice and serve warm.

Optionally top with whipped cream or a scoop of ice cream before serving.