Pre heat oven to 350 degrees F

Oil bottom and sides of 2 - 7" cake pans and line bottom with parchment. Oil parchment and dust pans with flour. Set aside.

CAKE:

In large bowl add the dry ingredients, flour, baking powder, soda, salt and stir to combine. Set aside.

In bowl of mixer fitted with the paddle attachment, cream the butter and sugar until fluffy and pale.

Add in one egg at a time, mixing between each addition. Scrape down sides of bowl if needed.

Add in the lemon zest and juice, keep mixing on medium speed.

On low, mix in the flour mixture, sour cream and milk, alternating as needed.

Mix on high for about 5 seconds to make sure everything is well combined.

Pour into prepared pans.

Bake 44-46 minutes or until the cake is firm and tooth pick inserted comes out clean.

Cool 20 minutes, remove from pans and place on wire rack to continue cooling completely.

BUTTERCREAM:

Combine sugar, egg whites, in medium sauce pan.

Whisk until sugar is dissolved, 2 to 3 minutes. Test by rubbing between your fingers; the mixture should feel smooth.

Pour mixture into bowl of mixer fitted with whisk attachment.

Mix egg white mixture until frosty, add the cream of tarter.

Mix egg whites again on med/high until glossy, stiff peaks form and mixture has cooled.

Reduce speed to medium and add butter 2 tablespoons at a time, mix until well incorporated. (mixture may appear curdled, keep mixing.)

Add in the lemon zest and juice. Mix well to combine.

Switch to the paddle attachment.

Mix on medium/high speed to smooth buttercream for about 2 minutes.

CANDIED LEMON SLICES:

In small sauce pan add the 1/4 cup water and 3/4 cup sugar, set aside.

Add the 1/2 cup dusting sugar into shallow dish, set aside.

In medium sauce pan add 2 cups water and lemon slices, simmer covered for 45 minutes.

Drain in strainer.

Heat the small sauce pan of sugar and water until sugar dissolves.

Add the lemon slice and cook for 15 minutes.

Remove lemon slices and arrange on wire rack so excess moisture drips off, about 2 minutes.

Then gently coat each slice of lemon with sugar on both sides. Return each slice to the wire rack to set, at least 4 hours.

ASSEMBLY:

Cut cake layers horizontally to equal four cake layers.

Lay first cake layer on cake plate.

Add layer of buttercream, I used a piping bag.

Repeat with remaining layers, adding layer of buttercream between each.

Crumb coat the cake on the sides and top. This is a "naked cake" so a crumb coat is all I did. Refrigerate for 30 minutes to an hour.

Pipe on a border and design as pictured or design of your choice.

Garnish with sprinkles and lemon slices.

Set in a cool place until ready to serve.

If traveling with this cake I would recommend refrigerating it for at least an hour. This will firm up the buttercream and make it less likely to smudge if lightly dinged.