Preheat your oven to 350°F (175°C) and prepare a 9x13-inch baking pan by greasing it with butter or cooking spray and lightly dusting it with flour.

In a medium mixing bowl, cream together softened unsalted butter and 1/2 cup of granulated sugar until light and fluffy, about 3–5 minutes.

In a separate bowl, whisk together 2 1/4 cups of all-purpose flour and 1 teaspoon of baking powder, then gradually add this mixture to the creamed butter and sugar until crumbly.

Press half of the crumbly dough evenly into the bottom of the prepared baking pan.

In a clean mixing bowl, beat together 8 ounces of cream cheese, 1/2 cup of sugar, 1 teaspoon of vanilla extract, and 1 egg until smooth.

Spread the cream cheese filling evenly over the crust in the baking pan.

Whisk together 3 eggs, 1 cup of whole milk, 1 teaspoon of vanilla extract, 1/4 teaspoon of salt, and 1/4 cup of sugar until smooth, then pour over the cream cheese layer.

Crumble the remaining dough over the custard layer evenly.

Bake for 50–60 minutes until the top is golden brown and the custard is set.

Allow to cool on a wire rack for at least one hour, then refrigerate for a minimum of 2 hours before serving.

Cut into squares and dust with powdered sugar just before serving.