Cake Layers:
Preheat the oven to 350°F (175°C) and butter and flour two 8-inch non-stick cake pans. Line the bottom of each pan with parchment paper for easy release.
In a large bowl, cream the butter, sugar, and lemon zest together until light and fluffy, scraping down the sides as needed.
Beat in the egg yolks one at a time, followed by the vanilla extract.
In a separate bowl, beat the egg whites until soft peaks form. Set aside.
In another bowl, whisk together the flour, baking powder, salt, and baking soda.
Gradually add the dry ingredients to the butter mixture, alternating with the yogurt. Mix until just combined.
Gently fold in the whipped egg whites until no white streaks remain.
Fold in the raspberries, being careful not to overmix.
Divide the batter evenly between the two prepared cake pans, smoothing the tops with an offset spatula.
Bake on the same oven rack for 30 minutes, or until the center of the cake springs back when lightly touched and the edges are lightly golden. Avoid overbaking.
Let the cakes cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely.
Lemon Buttercream:
In a large bowl, cream the butter until smooth. Gradually add the sifted confectioner’s sugar, followed by the lemon juice, and continue beating until the frosting is smooth and spreadable. If desired, add a small drop of yellow gel food coloring for a vibrant look.
If the frosting is too thick, add more lemon juice. If it’s too thin, add more sugar for a stiffer consistency.
Assembly:
Once the cake layers are completely cooled, place one layer on a cake stand and spread a generous amount of lemon buttercream over the top.
Place the second layer on top and frost the top and sides of the cake with the remaining lemon buttercream.
Slice and enjoy this zesty, berry-filled treat!