Preheat the oven to 350°F (175°C). Grease and flour two 8-inch (20 cm) round cake pans and line the bottoms with parchment paper.
In a medium bowl, whisk together the sifted all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, using an electric mixer, beat the softened butter on medium speed until creamy, about 1 minute.
Gradually add the granulated sugar to the butter and continue beating on medium-high speed until light and fluffy, about 3 to 4 minutes.
Add the eggs one at a time, beating well after each addition. Mix in the lemon zest.
In a small bowl, combine the fresh lemon juice, buttermilk, and vanilla extract.
With the mixer on low speed, alternately add the flour mixture and the lemon juice mixture to the butter mixture, beginning and ending with the flour mixture. Mix each addition just until incorporated; do not overmix.
Divide the batter evenly between the prepared cake pans and smooth the tops with a spatula.
Bake in the preheated oven for 28 to 32 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
Remove the cakes from the oven and allow them to cool in the pans for 10 minutes.
Run a knife around the edges of the pans to loosen the cakes, then invert them onto wire racks to cool completely, about 1 hour.
Once cooled, the lemon cake layers are ready to be frosted and assembled into a layered cake.