Preheat your oven to 350°F (175°C).

In a large bowl, cream together your softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, ensuring they are fully incorporated before adding the next.

In another bowl, combine your milk, lemon juice, and lemon zest.

Gradually add the wet ingredients to the butter and sugar mixture, mixing gently.

Sift together the flour, baking powder, and salt, and slowly fold this dry mixture into the wet ingredients.

Grease a baking dish (9x9 inches works great) and pour in your batter.

Bake in the preheated oven for about 35-40 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.

Let it cool slightly to allow the custard to form at the bottom.