Step 1

Preheat the oven to 350°F (180°C). Butter, flour, and line with parchment three 8-inch (20cm) round cake pans. Set aside.

Step 2

With an electric mixer, cream the butter and sugar until light and fluffy, and then add the eggs one at a time until fully combined.

Step 3

In a measuring cup with a pour spout, combine the milk, lemon juice, oil, lemon extract, and lemon zest. Gradually add the liquid to the butter mixture until thoroughly mixed.

Step 4

In a small bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Gradually beat into the batter just until evenly combined.

Step 5

Divide the batter between your prepared pans and bake for 30-35 minutes if using two pans and 20-25 minutes if using 3 pans, until a skewer inserted in the center comes out clean.

Step 6

Let cool for 10 minutes in the pans before inverting onto a cooling rack to cool completely.

Step 7

While the cake is cooling, prepare the lemon buttercream: with an electric mixer, beat the butter until light and fluffy, then gradually add the powdered sugar. Beat until fully combined.

Step 8

Into the butter mixture, pour in the lemon juice, cream or milk, and lemon zest and beat until combined.

Step 9

When the cake is thoroughly cooled, level your layers and frost.

Step 10

Store this cake at room temperature in an airtight container for up to 2 days.