How to Make It
Heat the oven to 350°. Line a 9-by-13-inch baking dish with parchment paper and spray evenly with baking spray. In a bowl, whisk together the flour, baking powder, and salt. Put the granulated sugar, butter, and vanilla in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-high speed until pale and fluffy. Add 1 of the eggs and beat until smooth. Add the dry ingredients and milk and beat on low speed until the dough just comes together and is smooth. Transfer the dough to the prepared baking dish and use your fingers to press it evenly into the bottom.
In a bowl, beat the cream cheese with a handheld mixer on medium-high speed until smooth and fluffy; add the remaining 3 eggs one at a time, beating well after each, until the mixture is smooth. Add the confectioners’ sugar and beat on low speed until smooth (if a few lumps remain here and there, it’s okay; they won’t matter in the finished product). Pour the mixture over the dough in the baking dish and spread out evenly with a rubber spatula. Bake until a toothpick inserted in the middle comes out clean and the top is lightly browned, about 40 minutes. Let cool completely, then cut into about 16 small squares (you want to keep these rich bites small—trust me).