Preheat the oven to 350°F (175°C) and prepare your cake pans by greasing them.

Cream the unsalted butter and sugar together in a mixing bowl until light and fluffy, about 3-5 minutes.

Add the lemon zest and egg yolks to the butter-sugar mixture and beat until well combined.

Stir in the vanilla extract, mixing well to incorporate it into the batter.

Whisk together the all-purpose flour, baking powder, salt, and baking soda in a separate bowl.

Gradually combine the dry ingredients into the wet mixture, alternating with the Greek yogurt.

Fold in the raspberries gently.

Beat the egg whites in another bowl until stiff peaks form, about 3-4 minutes.

Gently fold the egg whites into the cake batter until just combined.

Pour the batter evenly into the prepared pans and bake for 25-30 minutes.

Cool the cakes in the pans for 10 minutes before transferring them to a wire rack.

Prepare the lemon buttercream by creaming unsalted butter and confectioner's sugar until light and fluffy, about 4-5 minutes.

Blend in the fresh lemon juice, mixing until fully incorporated.

Frost the cooled cake with the lemon buttercream once it has completely cooled.