1. Prepare the Lemon Gooey Cream Cheese Layer
Add 8 oz (226 g) cream cheese, at room temperature to a large mixing bowl and beat on medium-high speed until completely smooth (1–2 minutes).
Beat in 1 egg, at room temperature and 1 egg yolk, at room temperature on medium speed until fully combined.
Add 1 tbsp (10 g) lemon zest and half of the 2 1/2 cups (325 g) powdered sugar. Mix on low, then medium speed until incorporated.
Add the remaining powdered sugar and mix just until combined. Set the bowl aside.

2. Prepare & Bake the Lemon Cake
Preheat your oven to 350°F (175°C). Grease a 9-inch springform pan and line the bottom with parchment paper.
In a small bowl, whisk together 1 cup + 2 tbsp (141 g) all-purpose flour, spooned and leveled, 3/4 tsp baking powder, 1/8 tsp baking soda, and 1/4 tsp salt. Set dry ingredients aside.
In a large mixing bowl (or the bowl of a stand mixer fitted with the paddle attachment), combine 3/4 cup (150 g) granulated white sugar and 2 tbsp (20 g) lemon zest. Rub them together with your fingertips to release the citrus oils.
Add 6 tbsp (84 g) unsalted butter, softened to the sugar mixture and beat on high speed until light and fluffy (1–2 minutes).
Add 1 egg, at room temperature, 1 egg yolk, at room temperature, and 1 1/2 tsp vanilla. Mix on medium-high speed until smooth and pale (1–2 minutes), scraping down the sides of the bowl as needed.
Alternately add the dry flour mixture and 1/2 cup (120 ml) buttermilk, at room temperature in small batches, mixing on low speed until a smooth batter forms.
Spread the cake batter evenly into the prepared springform pan using a mini offset spatula.
Pour the cream cheese layer over the top and spread it into an even layer.
Bake for 35–40 minutes until the edges are light golden brown and the center remains shiny with a slight jiggle.
Cool the cake in the pan on a wire rack for 45 minutes, then transfer it to the refrigerator to chill for 2 hours.

3. Prepare the Lemon Curd
In a small saucepan, whisk together 1/4 cup (60 ml) fresh lemon juice, 1/2 tbsp (5 g) lemon zest, 2 egg yolks, at room temperature, 6 tbsp (75 g) granulated white sugar, and a tiny pinch of salt.
Cook over medium-low heat for 12–15 minutes, stirring frequently, until the curd thickens enough to coat the back of a spoon.
Remove from heat and slowly whisk in 1/4 cup (56 g) unsalted butter, cold and cut into cubes until fully melted and integrated.
Transfer the curd to a heat-proof medium bowl. Press plastic wrap directly onto the surface of the curd to prevent a skin from forming, and allow it to cool completely.

4. Assemble & Serve
Remove the chilled cake from the springform pan and place it on a serving platter.
Pour the cooled lemon curd over the top of the cake, spreading it evenly with an offset spatula.
Serve at room temperature. (If chilled overnight, let the cake sit at room temperature for 1 hour before topping with lemon curd and slicing).