Make the lemon cake, preheat oven to 350 F (385 for high altitude).
In a medium-sized mixing bowl or bowl of a stand mixer, mix together cake flour, baking powder, baking soda, salt, sugar and lemon zest and mix until well combined.
Add butter and beat on medium-low speed until you end up with a fine crumb.
In a small mixing bowl, whisk together eggs, yogurt, mayo, lemon juice and vanilla until smooth.
Add the wet mixture to the dry mixture and beat on medium speed until smooth.
Slowly add milk and mix on low speed until just combined. The batter will be wet.
Bake for 35-40 mins until the cake springs back when touched or a cake tester comes out with just a few crumbs (30-35 mins for high altitude).
Next make the Raspberry Swiss meringue buttercream: In a large mixer with whisks or large bowl with a hand mixer beat the egg whites, sugar and salt for 5 mins until you get a thick white meringue.
While beating on medium add the butter 1-2 Tbsp at a time.
Once all the butter is mixed in add the vanilla and beat on medium high another 10 mins.
Puree the raspberries and lemon juice together in a food processor or blender.
Then add to the frosting, add ½ then tasted then added the other half.
Grind up the freeze dried raspberries in a food processor.
Make the white chocolate lemon ganache: Boil the cream (this can be done on the stove or in the microwave) and pour over the white chocolate.
Let sit for 5 mins to soften the chocolate then stir until smooth.
Add the lemon curd, start with 3 Tbsp and taste and go from there.
To assemble, level the cakes top and bottom. Leveling the top gives you nice even layers and trimming the bottom makes it so you don’t have brown cake crust in your cake slices.
Add a thin layer of buttercream to the cake then pipe a cake “dam” around the outside of the cake with a large round tip.
Fill that area with a thin layer of lemon curd (don’t add too much, it will squish out as you stack the cake if you do).
Then repeat with the next 2 cake layers and top off with the final cake layer.
Frost the top and sides of the cake and smooth.
Add Walkers Shortbread Fingers all around the bottom of the cake.
Drizzle the white chocolate cake all around the top edge, squeeze bottle but you can always just use a spoon too.
Fill in the rest of the top of the cake with more ganache.
Use a large star tip to top pipe large swirls across the top of the cake then add the Walkers Shortbread Rounds between the frosting swirls and you're done!