1. Preheat oven to 350°F (175°C). Grease and flour two 9-inch cake pans or line with parchment paper.

2. In a medium bowl, whisk together flour, baking powder, and salt.

3. In a large mixing bowl, cream the butter and sugar until light and fluffy. Beat in eggs one at a time, then mix in lemon zest and vanilla extract.

4. In a small bowl, combine milk and lemon juice.

5. Alternately add the flour mixture and milk mixture to the butter mixture, beginning and ending with flour. Mix until just combined.

6. Divide batter evenly between prepared pans. Bake for 25–30 minutes or until a toothpick inserted in the center comes out clean.

7. Let cakes cool in pans for 10 minutes, then transfer to wire racks to cool completely.

To make the frosting:
8. Beat softened butter until creamy. Gradually add powdered sugar, mixing well after each addition.
9. Add lemon juice and zest, then whip in heavy cream until frosting is smooth and spreadable.
10. Frost the cooled cake layers and decorate as desired.