Preheat oven to 180 degrees C (350 degrees F).
Mix Milk (180 milliliter) and juice from the Lemon (2 teaspoon) together in a cup to make buttermilk. Allow to stand for about ten minutes while making the rest of the cake.
Sift All-Purpose Flour (185 gram) into a bowl.
Add Baking Powder (1 teaspoon).
Add Salt (1 pinch).
Place Unsalted Butter (1/2 cup) and Granulated Sugar (250 gram) in a mixing bowl.
Cream butter and sugar together for about four minutes on medium speed.
Crack the Egg (2) into the bowl, and mix until combined, about two minutes.
Add Vanilla Extract (1 teaspoon).
Gradually add flour mixture, about a cup at a time. Alternate a cup of flour mixture with a third of the buttermilk.
Prepare a springform pan or cake tin by buttering and flouring the pan. Spread softened butter onto the cake tin, making sure to coat every nook. Add flour and shake pan to coat the butter in a thin layer of flour. Discard excess flour.
Pour cake batter into prepared tin.
Bake for 35-40 minutes, until golden brown.