Preheat your oven to 340°F.
Line three 6-inch round cake pans.
Mix the milk and vinegar together and let it sit to thicken.
Add the rest of the wet ingredients to the milk mixture.
Sift in the dry ingredients and mix until combined.
Pour the batter into the prepared pans.
Bake for 20-30 minutes, or until a toothpick comes out clean.
Let the cakes cool completely before leveling the tops.
Using a hand mixer or a stand mixer with a paddle attachment, beat the butter on medium-high until creamy and light. Gradually add the powdered sugar, scraping down the sides as you go. Mix in the lemon juice and extract.
Once the cakes are cool, layer them with the lemon frosting and enjoy!