Preheat your oven to 350°F (175°C). Grease and flour two 8-inch cake pans.
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Stir in the vanilla extract and sour cream.
In a separate bowl, whisk together flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, alternating with milk, until the batter is smooth.
Divide the batter evenly between the prepared pans and smooth the tops. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
In a mixing bowl, beat together the softened cream cheese, sour cream, THM vanilla extract, and a pinch of mineral salt.
Gradually add the powdered sugar, lemon juice, and lemon zest, and continue to beat until the icing is smooth and creamy.
Once the cakes are completely cool, frost the top of one cake layer with a generous amount of lemon icing.
Place the second cake layer on top and frost the top and sides with the remaining icing. Decorate with extra lemon zest if desired. Serve and enjoy!