Preheat oven to 350°F (175°C).

Grease a 9x13-inch baking dish with butter or non-stick spray.

In a mixing bowl, cream together unsalted butter and granulated sugar until light and fluffy.

Beat in eggs one at a time, then stir in vanilla extract until combined.

In another bowl, whisk together all-purpose flour, baking powder, and salt.

Gradually add the dry ingredients to the butter mixture, stirring until just combined.

Spread the dough evenly into the prepared baking dish.

In the same mixing bowl, beat together eggs, powdered sugar, and vanilla extract until smooth for the filling.

Pour the filling mixture over the crust in the baking dish.

Bake for 25 to 30 minutes or until the top is golden and a toothpick inserted comes out clean.

Allow the bars to cool completely in the dish before cutting into squares.

Optional: Sprinkle with sea salt on top before serving for a balanced flavor.