Heat the oven to 350°F. Line an 8x8-inch square baking pan with parchment paper, leaving an overhang on two opposite sides to form a sling. Lightly coat the pan and parchment paper with cooking spray.

Whisk 2 cups all-purpose flour, ⅔ cup granulated sugar, 1 teaspoon baking powder, and ½ teaspoon kosher salt together in a stand mixer. Add 12 tablespoons melted unsalted butter, 1 large egg, and 2 tablespoons finely grated lemon zest. Beat with the paddle attachment on low speed until crumbly, about 2 minutes.

Reserve 1 ¼ cups for the topping. Transfer the remaining to the baking pan and use the bottom of a flat measuring cup or your hands to press it firmly into an even layer.

Bake until the edges are golden brown, 14 to 20 minutes. Let cool for 10 minutes. Meanwhile, make the filling.

Wash and dry the stand mixer bowl. Place 8 ounces room-temperature cream cheese, ½ cup granulated sugar, 1 large egg, and 1 teaspoon finely grated lemon zest in the bowl and beat with the whisk attachment on medium speed until smooth, about 3 minutes. Spread over the crust.

Sprinkle the reserved crust mixture evenly over the filling.

Bake until set but the center is just slightly jiggly, about 30 minutes. Place the pan on a wire rack and let cool completely, about 2 hours.

Run a thin knife along the edges to loosen. Grasping the excess parchment, lift the slab out of the pan and place on a cutting board. Cut into 9 or 12 pieces.